Go Back   Aquarium Advice - Aquarium Forum Community > General Aquarium Forums > DIY Projects

Join Aquarium Advice Today
Thread Tools Search this Thread Display Modes
Please support our sponsors and let them know you heard about them on AquariumAdvice.com
Old 11-12-2011, 10:23 PM   #31
Aquarium Advice Freak
SAAVE853's Avatar
Join Date: Aug 2010
Location: Miami Beach, FL
Posts: 275
Originally Posted by Floyd R Turbo
Your lights are pretty far away. Should have then about 4 or 5 inches away.

Good growth for 3 days
You got any good ideas laying around on how to mount those lights to get them a bit closer?

Live & Let Live!
SAAVE853 is offline   Reply With Quote
Old 11-13-2011, 10:24 AM   #32
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
There is no mechanism in the ocean that mimics a skimmer. The beach, maybe, with the foam washing up, but compare the amount of water/life in an ocean, even if you restrict to the areas near a beach, and the amount of foam fractionation taking place is a ridiculously low percentage compared to the average skimmer.

Skimmers take out organics - food. Scrubbers take out the inorganics - the result of processed food. Scrubbers allow the animals in your system to completely break down the food you give them before removing the waste, compared to a skimmer which removes the food before your animals can get to them, and cannot remove inorganics.

If you run a scrubber only, and dose Kalwasser or use a calcium reactor, you should be fine. If you use a BRS 2-part type supplement, then you will get some salinity creep and will probably want to do a 5% PWC / month to re-adjust ionic levels. Otherwise as long as N and P are in check and all the corals and fish are healthy, you're good to go.

There are plenty or people running scrubber-only systems. I have been for over a year with almost zero issues.

My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:02 AM   #33
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682

In the past 6 months, there have been several basic changes to the core concept of the Algae Scrubber, and these changes resulted in many people experiencing better growth and more effective filtration.

By far the biggest change is that the size of the screen needed for a given system is no longer dictated by the volume of the tank or the bio-load, but is instead based on the amount of food you add to the system. This has resulted in much smaller screen requirements; in some cases, ridiculously small screens when compared to the previously guidelines.

The second is the optional lighting scenario using twice the light intensity and half the photoperiod, which can power through the initial dark algae growth stages some experience, and can also be helpful in battling tough tank algae.

Third covers the advent of LED Algae Scrubbers.

I went through and edited the previously posted “Basics”, mainly for the purpose of addressing the 3 above items. Many other sections were also affected, and I have incorporated as many hints, tips, and tricks as I could. Even if you have read through the previous “Basics” summary before, read this one again. And again.

Some of the pictures in this are based on the old sizing requirements, but are still good for examples of specific principles. For this reason, and the lack of pictures of smaller builds using the new requirements, I have kept many of the pictures the same.

Part 2? Yeah yeah…I incorporated a little more into this one, and I have a start on Part 2, but it needs revamping too!

This will likely be the last summary revision for this version of the Algae Scrubber. There is a new version being developed (not by me) and it is currently being kept under wraps as it is in the middle of the patent process (again, not by me) so I know very little about it, except that it will supposedly have vast improvements in many areas, and will not resemble any Algae Scrubber that anyone has ever seen (this frustratingly includes me). The principles are all the same, so this summary has value still. But just be aware that a lot of this information (that I’ve but so much time into assembling…grrr!) might just get thrown out the window. Tidbits of info? On the new version, you won’t have to cut a slot in a pipe, can remove and clean the screen without shutting off flow,

Anyways….the re-revamped Basics:

Algae Scrubber Basics Summary: February 2012

There are many options when it comes to building your own Algae Scrubber. Hopefully this series of posts will wrap up all the basic concepts as clearly and concisely as possible. It seems that many people look at this concept and think they can make some kind of major improvement, and post their idea. Then, a newbie can look at that and think that it makes great sense and mimic it, without understanding the pitfalls. I feel that it is important to understand the concept and purpose behind the basics, and why you should rarely deviate from them without fully understanding the basic concepts first.

Most of the issues people encounter with their DIY builds can be directly attributed to missing one or two of the basic principles. So consider this a "best practice" summary. That is, there are several ways to build an Algae Scrubber, but there is always a cheap and easy way, as well as the most effective and efficient way.

The Vertical Waterfall Algae Scrubber

99% of this summary is dedicated to the basic of designing and constructing a modern, vertical screen, waterfall-style Algae Scrubber, illuminated from both sides. This is simply because this design is currently by far the most efficient and effective type of Algae Scrubber design, and the only one that I recommend building. The occasional mention is made regarding considerations to make for building a single-sided Algae Scrubber, or for a horizontal/slanted Algae Scrubber. From here forward in this series of posts, horizontal or slanted Algae Scrubbers will be referred to as “non-vertical”.

The vertical waterfall style Algae Scrubber is very efficient for a couple of reasons. The design allows you to illuminate the algae from both sides and place the lights very close, which reduces the distance that light has to travel through water in order to reach the algae. The water flow over the screen is relatively thin and moves fast; this is important, because algae requires turbulent flow in order for nutrients to reach the cells on a microscopic level (Google “boundary layer”). Because of both of these factors, vertical Algae Scrubbers require less light and material than the older style non-vertical Algae Scrubbers for equivalent filtration capacity.

The Slot Pipe, Screen, and Fasteners

The principal component of the modern vertical waterfall Algae Scrubber is the slot pipe and plastic canvas screen. The screen is inserted into a section of horizontal PVC pipe which has a slot cut into it. The screen is typically held in place with a fastener through a cut-out section of the screen, like this:

Slot Pipe

The slot pipe itself should be Schedule 40 PVC at a minimum. Don't use vent pipe, flexible hose, or thin-walled PVC. The reason is that cutting a slot in the tube weakens it enough that it can bow over time and cause the slot to change width, and cinching zip ties tightly around it can make that worse. This is especially true for a wide, tall Algae Scrubber. Anything over 24" should probably have 2 slots, with a small section in the center left uncut (maybe 1/4") with some kind of means of support at the center. It may look fine at first, but with heavy growth, you start to see this:

I'm not saying that it won't work, and I'm not critiquing the design pictured above. It just got me thinking that it can't be good to have that pipe flexing that much. So this is a recommendation I am making for Algae Scrubbers with screens over 24" wide. But check out that growth!!! That's 6.5 pounds of algae (drained).

NOTE: I left that above section in here because I just love that picture. But the reality is that unless you are feeding about a 1/4 cup of food per day, you’ll never, ever need an Algae Scrubber this big. Read on…

Pipe Diameter

When running an Algae Scrubber fed directly from the overflow, there is usually no need to deviate from the size of the drain pipe that you currently use. But, that all depends on your total resultant flow to the pipe, length of screen, etc. In the majority of cases, this doesn’t change anything. However, if you had a large tank, and were combining four 1” drain lines together to feed one large Algae Scrubber, you have different considerations.

If you're doing a pump fed Algae Scrubber, either top of tank or sump, try to match the size of the slot pipe and other PVC components to the recommendations from the pump manufacturer, and if in doubt, err on the side of larger pipe. Larger pipe puts less head pressure on the pump, which will increase the flow rate.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:03 AM   #34
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
Cutting the Slot

The width of the slot should be approximately 1/8" wide, the same length as the screen which you are using (as exact as possible), and as straight as possible. Cutting a straight, even width slot is arguably the most difficult and critical part of building an Algae Scrubber. If the slot is crooked or uneven, the screen may not hang properly, and there may be areas where the flow is lighter and heavier. This can result in sections of weak growth.

The width of 1/8” is what works best for a screen that has about 35 GPH of flow per inch of slot length. This flow rate is the minimum ‘target’ flow rate you want to have. At this rate, the water will ‘pile up’ in the pipe and purge the air out, and the water drain out fairly evenly across the entire screen.

Cutting the slot too narrow will result in low and uneven flow across the screen, resulting in areas of low growth. If you feed the scrubber via the overflow, this can cause big problems. Water can only flow so fast through a certain opening, and while this flow will increase with pressure, there is still a limit.

Cutting the slot too wide can also result in problems. If the slot is too wide for the total flow, then the air does not purge from the pipe as easily, resulting in the water ‘shooting’ through the pipe and dumping out on the far end. The only reason to widen a pipe is when you want a greater flow rate per linear inch of slot. It doesn’t take much of an increase in width to allow a significant increase in flow. If you think about it, the 35 GPH/in slot is 1/8”, and half of that is take up by the screen, which means 35GPH/in flows through a slot that is essentially 1/16”, maybe 3/32” if you don’t count the screen as completely blocking half the flow (since it is mesh after all). So increasing the slot width by 1/16” can likely allow double the flow. For your Algae Scrubber to be successful with a wider slot, the screen really needs to be rough enough, so just pay attention to that when roughing up your screen for a high-flow setup.

However you go about this, you might need a few tries to get good at it. PVC is cheap, so practice on a small section so you get used to how this is done. It’s going to take a little time and patience – don’t rush it. Mark the slot, and cut carefully. If you mess up, do it again. Once you solvent weld an end cap and a union to it, it is not as cheap to replace (but still relatively cheap).

Doing it right means using a power tool.

You could use a Dremel with a cutoff wheel

An Oscillating tool:

A roto-zip (and a guide jig) or a router

Plastics like PVC are ‘grabby’, and using a roto-zip or router takes extra precautions - so this is not for the inexperienced, but it makes very straight slots. With the right jig setup, you could also use a handheld circular saw, but then you are lowering a spinning blade onto the PVC (if you’re cutting the slot in the middle and leaving the ends uncut).

One of the best ways to cut a perfectly slot straight is by using a table saw. However, there really is no way to cut a slot in the middle of a section of pipe (or across the whole length of one side of a pipe) without removing the anti-kickback device and lowering the pipe on to the spinning blade. I have successfully done this, and it is definitely not for the person who is not fully respectful of power equipment and comfortable with the above mentioned method (or any of the other methods, for that matter)

However you decide to cut the slot in the pipe, remember to observe all necessary safety precautions. Either that, or have someone else do it for you.

I read a post from one person who reported that they had their table saw grab the piece of PVC pipe while cutting the slot and shoot it across the room. Turns out he had the blade too high and the pipe rotated on him as he wasn’t using a fence of any kind to guide the pipe. Be smart and careful.

Screening Material

The search for the "perfect material" for growing algae in the vertical waterfall configuration has always come back to the same material, the Clear #7 Mesh Plastic Canvas. This can be found at almost any fabric (Jo-Ann Fabric) or craft-type hobby store (Michaels), usually in the knitting materials section. I have seen it at Wal-Mart, next to all the yarn. If you google “plastic canvas” you’ll find hundreds of links. You can feel free to experiment, but this material has been proven to work over and over again.

The reason that it works so well is because it is cheap, flexible, light, and easy to rough up. It is also translucent, which is critical. As algae grow thicker on a screen, the outer layer starts to block light to the lower layers. This causes weakening of the algae at the point of adhesion to the screen material. Allowing light to penetrate to the base of the screen from both sides helps to prevent the lower layers from weakening and detaching from the screen. Any material that blocks light is fundamentally inferior, all other things being equal. This also means don’t use any of the colored screening materials that you will see.

A brand new screen is slick and smooth. Except for the top edge of the screen, it needs to be roughed up so that the algae has anchoring points. This is a critical step and it absolutely must be done properly. Once the screen is established, algae can grow very thick, it can hold a significant amount of water, and it will get heavy. I have seen pictures of screens that weigh several pounds. This weight is distributed across the screen, and with a rough base, it will hold very well.

To rough the screen up, the best thing to use is a bi-metal hole saw. These saws have teeth that protrude out to a sharp point, and are great for tearing up the screen

As the above picture shows, you need to drag is back and forth across the screen. I suggest you sit in the garage or outside with a cutting board on your lap and lay the canvas on that. When you start roughing the screen, do a lot of random movements. Don’t concentrate on one spot for very long or you’ll wear through the screen and tear it. Rotate the screen often. You can also tilt the saw bit as you drag it so that the teeth won’t snag the screen. You should get a good heaping tablespoon of plastic from each side of a 10x10 screen.

After it’s all done, your screen should look like this:

Give the screen a good rinse and a light scrub with an old toothbrush to clear off all the pieces that are ‘hanging by a string’. These pieces are inert plastic, but still, you don’t really want these floating around in your aquarium.

Though I haven’t used one myself, I have heard that a rasp (available at any hardware store) is also great for roughing up this material. There are handheld rasps (similar to a Ped-Egg for your feet, except much sharper), and there are bit-mounted rasps (for power drills). It looks like it could be a little easier to tear the screen with this tool, but there is much less elbow grease involved. The drill bit rasps I have seen don’t appear to have protrusions large enough to “dig” into the screen and result in a cactus-rough surface.

Some have tried other methods of roughing up the screen. 80 grit sandpaper will definitely rough up the screen, but it doesn’t leave it ‘prickly’, so it’s not very effective. Recently, someone put a screen in the oven for a few minutes, then sprinkled it with aragonite sand and pressed it on. It was a neat idea, but it blocked the light from penetrating to the base from both sides, so it didn’t do very well.

The bottom line here is that there really is no shortcut. You only have to rough up the screen once, so stick to the tried and true method, unless you feel like experimenting on your aquarium.

As previously mentioned, the top edge of the screen (where it is inserted into the slot pipe) should not be roughed up at all, or else algae can easily grow into the slot and restrict the flow. The amount of material you leave smooth depends on your design, mainly, how far you plan on inserting the screen into the slot pipe. Regardless of this measurement, the smooth section should extend at least 1/8” down below the slot.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:04 AM   #35
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682

Most people have uses standard zip-ties to secure the screen to the slot pipe, since they are cheap and easy to use. Generally you have to use new ones each time you clean the screen (because you have to cut them), or you can re-use them if you’re handy with the tip of a razor blade and can get them to release.

You can also use releasable zip ties (I found them in the electrical section of Home Depot), but they’re not as easy to release as you would think they would be, unfortunately. I have used them, and I still need a mini-screwdriver to take them off.

Velcro straps can also be used, however they need to be free of adhesives, and I have never been able to get an answer from manufacturers about the stuff that has hooks on one side and loops on the other (such as OneWrap) regarding their safeness in aquaria. “Medical Grade” would be the safe way to go, but I haven’t looked much into those.

Another method of holding the screen in place is to use plastic shower curtain rings. It works very well, however you should have extras on hand in case one breaks when you’re removing it.

Yet another is to use sections of PVC pipe, one size larger that the slot tube, to make rotatable rings. This works very well, just make them narrow so that they don’t block too much flow.

The best one that I have found to date is the nylon beaded cable tie, which, like the zip-tie, is inert, but super-easy to release, so it’s good for months and possibly years. I haven’t seen these in any store, I had to order them online.

The ones I bought are perfectly sized to fit around a 1” PVC Schedule 40 pipe. These are my personal favorite choice. If you hang the screen only from the center (with the screen touching the top inside of the pipe) then these might not work very well. Instead, use them at the corners of the screen. Another nice this is that the beads are just a little bigger than the #7 mesh screen holes, so you can just push them through very easily.

TIP: This is an important point – if you have a screen or screens that are held in place in the center of the pipe (or anywhere away from the ends) you do not want to cinch cable ties down hard! Since there is a slot cut in the pipe, cinching down the ties will cause the pipe to pinch closed and you will get reduced flow in the center. The zip-ties should just be snug enough to hold the screen in place.

I’ve seen a few designs that don’t use fasteners, but there are considerations to make with these designs.

Preventing water creep along the pipe

This is an important part of the slot pipe design. The issue here is that when you are running water though a horizontal pipe with a slot in the bottom of it, the water has a tendency to creep along the bottom edge of the pipe, not matter how perfectly horizontal you install it. If your Algae Scrubber is positioned completely over your sump, this may not be a big issue, as any errant flow will just drip into the sump. If your pipe ends extend close to the edge of the sump however, a steady trickle of water can result in gallons of water on the floor. I can attest to this.

The solution is very simple. Right at the point where the slot ends, place a large plumbing gasket, such as an o-ring (use several, they’re cheap), or even a bulkhead gasket. The point is that it needs to prevent water from getting past it. I can tell you from experience that a standard zip-tie will not work – the profile is too low.

In many cases, you need to put this piece on the pipe before you weld the cap on the end of the pipe, or else it will be very difficult to install. This one is a ballcock washer, and definitely needs to be installed before the cap is installed:

Here’s what I used on the latest mod to the Algae Scrubber I run

I found these at Ace hardware in the plumbing gasket section. I forgot to put them on before solvent bonding the ends on, but luckily they were flexible enough to get over the end cap. They work fantastic!
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:06 AM   #36
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
As far as spray and salt creep is concerned, you want to avoid buildup on the lamp itself. No matter what you do, there will still likely be some buildup due to evaporation, so you will want to wipe off the lamp or fixture periodically (as needed). Make sure the lamp has cooled down, remove the lamp if possible, and wipe it down with a soft cloth and warm water. This is rather easy to do in place with T5HO lamps, and more difficult for spiral and multi-tube CFLs; just be gentle so you don’t crack the tube.

The water will cascade down the screen smoothly, and then drop off the bottom edge. If you don’t let the bottom of the screen sit in the water, it’s going to pour off and crash down, and splash everywhere. That’s not the problem I’m discussing here, I’m talking about spray from the slot pipe or screen.

The ideal solution is to block the source of salt creep or spray – the slot pipe itself. While 99.99% of the water that cascades down the screen will stay on the screen, occasionally there will be droplets of water that pop and fly around, and over time these can cause salt creep.

The most recent and effective solution to the spray issue is also one of the cheapest and simplest. Saran Wrap!! I don’t have a picture of this, so just use your imagination: take a piece that is a little longer than the slot and wide enough to wrap around the pipe plus about an inch or so, drape it over the pipe, and touch it to either side of the screen. Water tension does the rest, and the Saran Wrap suctions onto the screen. Presto. No spray (from the slot). You still might get some droplets randomly flying off the algae mat, so other protection might be necessary, but the slot spray is definitely the biggest culprit, and Saran Wrap is a great weapon.

Aside from Saran Wrap, the best spray blocker is a box that totally encloses the screen on all 4 sides and bottom, and has a removable lid. Such a box would have a drain hole in the bottom, and would typically be made out of acrylic, but could be made from glass also. This is beneficial for other reasons too, but we’re just talking spray blocking right now.

Closing the top with a lid, or at least extending the blocker up to the top of the slot pipe, will minimize the random drops that occasionally fly upward, as well as evaporation. A lid should not lip over the outside of the box, rather the inside so that any condensation will tend to stay inside the box.

The next best would be an enclosure with an open bottom. The advantage to an open-bottom enclosure is that it's easy to build. If you extend the screen to the water level inside the sump, you can nearly eliminate noise and microbubbles. Pictures illustrate this best:

The most basic full-screen spray blocker would just be a couple of plastic panels draped over the tube. Here are a few examples:

I don’t recommend enclosing CFLs in glass or plastic jars. IMO, it is difficult to allow for adequate air convection with such an arrangement. CFLs get hot even with air convection, and if a hot lamp gets in contact with the plastic, it could melt and might start a fire.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:07 AM   #37
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
Planning your Algae Scrubber

There are 2 basic ways of supplying flow to an Algae Scrubber: directly from the overflow, or from a dedicated pump.

The above diagram does not illustrate the top-of-tank Algae Scrubber, which would apply to someone running a sumpless system, however this is just a modification of the pump-driven Algae Scrubber with the pump in the display tank.

The very first step you need to do before buying, measuring, or sketching up anything, is to decide how you are going to supply your Algae Scrubber, and determine what your available flow rate is.

Available Flow

In any case, you need to measure the flow rate. Do this step. It is critical. Do not, I repeat, do not calculate the flow rate based on pump curves and head-feet of pressure. This may sound like a total pain in the behind, but just trust me on this one. Would you rather go through all the effort of building an Algae Scrubber, only to have problems and find out that you didn't have as much flow as you thought you did? Believe me, I've been there.

If you've been reading this thread, you will see that at some point I started making a big deal about this. The reason is that it is a big deal and I think many people don't realize that their pump does not pump at the rated flow, and in the majority of cases, it doesn't come close to the flow calculated by using a standard head-foot calculator program or table. So I have chosen to make it the #1 priority for an Algae Scrubber design, hands down. You have to know your actual flow.

For a drain fed Algae Scrubber, fill a pitcher with the water entering the sump. You will probably need to rig up a temporary pipe or routing configuration so that you can fill the container. For a pump-fed Algae Scrubber, set up the pump in a sink filled with water to the same level as your pump will be submerged, and connect the tubing required to reach the height of the connection to the horizontal slot tube, so that you mimic as best as possible the actual conditions. Backpressure created by the slot/screen is negligible unless your flow rate significantly exceeds 35 GPH per inch of slot length.

Now that you've done all this, fill the container and record the time it takes to fill it. Do this at least a dozen times. The way I do this is by using a recording device, like a digital voice recorder, and just calling out "Go" and "Stop", then afterward, playing it back and using a stopwatch to get the time intervals. You could also have someone else run the stopwatch and write down the times. Average out the times and then figure out how many gallons per hour of flow you are actually getting. If you have multiple drains, measure and extrapolate GPH for each individually, and then add together.

For instance, if you are using a 1/2 gallon pitcher, and it takes 4.5 seconds to fill it, then you would have (0.5 gallons / 4.5 seconds) x (3600 seconds / 1 hour) which would be 400 GPH.

Don't be surprised if you have a lot less flow from your pump than you thought you had. I had less than 1/2 of what I thought it was. Head-feet calculations are usually way off, because most people don't use big enough return hose or have other restrictions in the plumbing. Some of it is inherent to reef-ready aquarium design (1" drain, 3/4" return, Danner Mag-Drive 9.5 and larger pumps need 1.5" return, see a problem?). So don't feel bad. A lot of people are in your situation, but they just don't know it.

Start with a clean pump. If your pump is not clean, soak it in vinegar for 15 minutes and scrub it good. After running an Algae Scrubber for about 4-5 months, your pump flow will drop about 15%, and by 6 months, it will have dropped by 25%, so you want to know your best-case flow and build around that. It's a lot easier to start with a throttled-back clean pump and open it a little when the flow rate decreases. Figure out your system flow rate, multiply by 80%, and that will be a good starting point. But, it's not going to kill you to start at full flow, and end up with a little less over time. You might just want to clean your pump a little more often, say every 3 months. So it's up to you. Just being aware of your system conditions puts you miles ahead.

Big Basic Change #1 - Screen Size

Originally, the standard method used to calculate the screen size required was based on the size of the tank. Around September 2011, that method was revised to be based on feeding amount. This is a very important change, because not only does it mean an Algae Scrubber screen is more appropriately sized, it also means you will get better growth results. As it turns out, bigger is not necessarily better when it comes to your algae screen – the algae on a screen that is too large compared to the amount being fed will become nutrient deficient over time as the algae will want to grow across the entire screen. Concentrating this algae growth down to the appropriate size in accordance with the amount fed means you will typically get more green growth, and green hair algae is what filters the best (and smells the least, I might add).

The good news here is that this means that in most cases, you can get away with a significantly smaller screen, and guesstimating your bio-load specific to your system is completely unnecessary.

Once you figure out your available flow, then it's time to figure out your optimal screen dimensions.

There are 2 ways of looking at this: square inches based on length and width dimension, and square inches based on illuminated surface area. The latter is technically more accurate, but since most people light both sides, the former is usually referenced.

The new rule is based on cube-equivalent amount of food fed daily, regardless of how many gallons you have in the system. You need 12 square inches of screen illuminated on BOTH SIDES with a total of 12 watts of fluorescent light for 18 hours/day for each cube-equivalent fed into the system per day. That means 6 watts per side of real wattage, not equivalent wattage. LED wattage is addressed separately as it has a different set of rules.

The cube-equivalent is defined as any ONE of the following:

1 frozen cube
10 pinches of flake food
10 square inches (60 sq cm) of nori
0.1 dry ounce (2.8 grams) of pellet food

3.25 mL of liquid coral food

If you feed something else and are having a hard time determining the cube-equivalent, then take the daily amount of food, put it in a blender with some water and puree it well, then strain it using a coffee filter (or a rotifer sieve if you happen to have a spare one laying around) and pour the food into an empty Ocean Nutrition or other cube-type food tray, and you will have the cube-equivalent for that amount of food.

If you light the screen from only one side, double the dimensional measurement of the screen; light requirement is the same, it’s just all on one side.

For a non-vertical screen, double the dimensional measurement again. Any screen that is not 100% vertical is treated as a horizontal screen (even if it’s only slightly slanted). This is because of the channeling properties inherent to a slanted or horizontal screen; there is an immediate loss of efficiency when the screen is non-vertical.

So, just so we're 100% clear on this:

Vertical, lit from both sides: 12 square inches of screen material per cube of food per day, 12 watts of light split between each side.

Vertical, lit from only one side: 24 square inches of screen material per cube of food per day, 12 watts of light on one side.

Non-vertical: 48 square inches of screen material per cube of food per day. Lighting must increase by a factor of 1.5 (discussed in the lighting section). In this case, a MINIMUM of 18 watts of light is needed, preferably much, much more.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:09 AM   #38
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
Screen Dimensions

So now that you know your actual flow rate AND the necessary size of your screen (dimensional area), now you are ready to figure out your dimensions.

You want the flow to be a minimum of 35 GPH per inch of screen width. You can get by with a lower flow rate, but your Algae Scrubber may not be strong enough depending on your bio-load. You can have higher flow also, which is generally not a problem as long as your screen is rough enough and you aren’t getting black slime algae (which is a sign of high nutrients, and needs more frequent cleaning until it lightens up). What you want to achieve is enough flow so that you have a full sheet of water across the screen off the bottom edge, like this:

Simply take your GPH (that you just measured) and divide by 35, and this will be your maximum screen width. Then, take that number and divide it into your total screen area to obtain the height dimension of the screen. The result is the total area of roughed-up screen that you want.

You want to add to the height dimension for the section of smooth screen that will be inserted into the slot pipe. You want to allow for the distance that the screen will be inserted into the slot pipe, plus at least 1/8" of smooth screen below the slot tube to help prevent algae growth into the slot. The total amount of smooth screen you need depends on how far you insert the screen into the slot pipe. A little extra smooth screen at the top never hurts, as it can be trimmed off later if you leave too much.

You may also want to leave smooth screen at the bottom as well. Most screens, in some form or another, will ‘dip’ into a pool of water at the bottom. This submerged area does not grow algae very well, so you can leave that smooth too.

The critical area, and the only area that contributes to scrubbing power, is the roughed-up and illuminated portion of the screen. Figure out your necessary screen dimensions, and then add the extra smooth sections to the height dimension.

If the only way you can mount your scrubber is to have it hanging in free air and high above your sump, you can leave a significant amount of smooth screen below the ‘effective’ area, or you can attach another screen to the bottom edge of the main screen. You may end up with some gooey growth on this screen though, so you should avoid it if possible (IMO).


There are 3 basic types of light sources that people use: CFL, T5HO, and LED.

Since LED Algae Scrubbers are becoming all the rave, I have further expanded the discussion regarding LEDs. The LED based Algae Scrubber has a different set of rules to follow with respect to wattage and photoperiod, as well as a few other factors. So to avoid confusion, I kept the LED section separate and it follows the fluorescent section.

In the cases of fluorescent lighting, the optimum spectrum / light temp for growing algae is 2700K-3500K, with 2700K-3000K getting the best results.

Proper wattage of light and proper flow to the screen are the critical factors; color temperature / spectrum comes in behind those. You can use higher K ratings, but the real-world (anecdotal) evidence suggests that the optimal range for growing algae is heavy in the red spectrum. If you look at regular plant grow lights, you will find that most of them (especially LED grow lights) are very heavy in red.

Power Compact, or PC lamps, are not recommended, because they run way too hot for the amount of light you get out of them. I don't even care for them for tank lighting.

Quantity of lighting is dependent on the size of the Algae Scrubber screen (dimensional area). In general, you want 1 watt (actual, NOT “incandescent equivalent”) of light per square inch for optimal scrubbing power. You can get away with less, but I would not recommend it. You will likely experience problems at some point.

As you will notice throughout this thread, it is generally stressed to follow the minimum 1 watt per square inch guideline. This is because it solves many Algae Scrubber issues. The reason behind this is scientific. Light interacts with algae and causes N and P (and ammonia & nitrite, among other things) to be absorbed, and chlorophyll is created (among other things). The more light, the more nutrient reduction you get. There is a direct correlation between the quantity of light supplied and the amount of nutrient reduction capability.

A non-vertical Algae Scrubber requires at minimum 1.5 times the light as you would need for a comparable vertical single sided Algae Scrubber. Here is where I will switch to the total surface area method. A vertical single sided 1-cube per day Algae Scrubber would be 24 square inches, lit with 12 watts, or 0.5 watts per square inch of total surface area. A non-vertical Algae Scrubber needs to be 2x as large, or 48 square inches, and have 18 watts of light, which results in 0.375 watts per square inch. I would argue that you need at least 0.5 watts/sq in, if not a full 1.0 watt per square inch to make up for the efficiency loss factor inherent to a non-vertical Algae Scrubber because of channeling and/or water draining through the screen instead of across the algae mat. Older dump-bucket or surge style Algae Scrubbers may not have this problem, but then again, you’re only filtering when the water is moving fast, which is only periodically (again, boundary layer). I hope this convinces you not to try a non-vertical Algae Scrubber, unless you just think it would be cool.

In general, you need to run your lighting for 18 hours on, 6 hours off (see UPDATE below). All life needs downtime. Plants are no exception. They have adapted to the environment over millions of years, and as the saying goes, you can’t fool Mother Nature. So don't go thinking that you can run lights 24/7 and get 25% more algae growth, it doesn’t work that way. The lights should be run on the reverse cycle of your display tank lighting; this assists in maintaining pH at night, as well as spreads the light-induced heat load more evenly throughout the day.

You want the lights as close as possible, within reason. The effective power/intensity of light follows the inverse square law. If you move a light twice as far away, the intensity drops by a factor of 4. If you move it twice as close, you get 4x the intensity. The balance point seems to be about 4" from the screen for CFL, and about 2" with T5HO. The reason for 4" away for CFL stems from hot spot issues due to the concentrated signature of the lamp; CFLs need to be a bit further away to cover the proper area without too much intensity. T5HOs do not have this problem, as the light is very evenly spread.

As far as spacing is concerned, CFLs need to be spaced according to the allowance of the design. If you need 2 per side, just position them for the best coverage. This is really on a case-by-case basis.

The advent of the smaller, higher light screen (discussed in detail to follow) has presented an issue with respect to CFL Algae Scrubbers – how to fit all that light into an even smaller area! There is no rule saying that you cannot trim the CFL reflectors so that they can ‘cross over’ each other. I literally just thought of this as I was editing this. Think of it like when you’re watching a movie and someone is looking through binoculars – you see the “8”-on-it’s-side shaped viewing area. Just trim both reflectors where they intersect using some tin snips or a wire cutter. (Be careful of sharp edges!) You may lose a little light from one lamp that is throw to the adjacent lamp (which it can now “see”) but since we’re concentrating the screen down in size, we need acceptable losses, and this is one. There are also socket splitters that you can use so that you can put 2 CFLs into one socket. However, you lose a little more with this method because the lamps will extend out from the reflector.

As for T5HO, you generally want a lamp spacing of 2-3". For T5HO, your Algae Scrubber will generally need to be designed around the lamps and spacing. CFLs are more flexible in this respect, allowing a variety of configurations.

If you run your lighting 18 on/6 off, the lamps must be replaced every 3 months. This is not just a rule for Algae Scrubbers, you will see many people make this suggestion for refugium lighting as well. That is because there is a power drop-off and a spectrum shift that takes place over time, and when you go much past 3 months, you hit that drop-off point. We can't see the difference, but then again, we're not algae - it can. The result is that your screen will slow down growing and reduce filtration, which you do not want.

The light source needs to be positioned so that it is pointing directly at the screen material. Do not place the fixture so that it points parallel to the screen (from the ends or the top), place it so that directs the light toward the screen. Perfectly perpendicular is optimal, but if you have to point it at somewhat of an angle just to make it work, that will be fine. This is more of a concern for CFL than linear sources (T5HO), however I have seen a few T5HO build with the lamp 4 inches above the screen, shining straight down. They didn't work so well.
My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:10 AM   #39
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
Big Basic Change #2 – Alternative High-Intensity Lighting

Around the same time that the screen sizing method was changed, another suggestion was made: you can use twice the wattage of lighting and cut the photoperiod in half. This has a couple of advantages:

The first and primary advantage is the fact that more intense light promotes greener growth faster. This is especially useful in systems that have an initially high nutrient load, or systems that are overrun with algae in the display tank. More intense light will penetrate deeper into the algae mat. In a high nutrient system, the screen tends to grow darker (brown or black). This dark growth prevents the light from reaching the ‘roots’ of the algae, which may lead to the algae detaching from the screen more easily between cleanings. In systems that have a lot of algae in the display tank, it is more difficult to establish a preferred growth location (the Algae Scrubber screen); increasing the light level on the screen can greatly assist in this battle.

The second advantage is increasing lamp life, or more accurately, increasing the time between the need for lamp changes. Since you are only running the lamps half the time, they will last twice as long. This is of course offset by the need for twice as many lamps, but if you combine the new screen sizing guideline together with the higher-light guideline, in most cases you are reducing the overall wattage requirement by half or more versus the old tank-size guideline.

The caveat to this rule is that you must keep an eye on the type of growth. You want green hair algae; anything else requires an adjustment to the ON cycle. If you are getting dark growth, then you need to increase the photoperiod. If you are getting yellow growth, you need to decrease the photoperiod. I suggest making adjustments in 1 or 2 hour increments per week until you get the desired green growth.

Also, as the lamp will eventually start to weaken, you need to pay attention to your growth. Around the 3 month point, the growth may start to get darker. If/when this occurs, you will need to start increasing hours until it grows green again. When you reach 18 hours, it's time for new bulbs. Keeping track of the “on” time that you use will greatly assist you, as you will be able to see a pattern developing. Growth can vary from week to week, but should be relatively consistent on the long term, as long as nothing else changes; changing feeding amount, rearranging the tank, adding more LR, an unknown dead fish, etc, can all affect the color of the growth. Constantly fiddling with the photoperiod should not be necessary after the Algae Scrubber is “dialed in”. You should only need to adjust upward about 1 hour per week as the lamps weaken.

NOTE: Yellow growth is a spongy, gooey type of growth that is also great at light blocking, and is a result of not enough nutrients being delivered to the screen/algae in proportion to the light provided. To resolve this, increase flow if possible, add iron, or reduce the number of hours. You can also increase feeding as long as it’s not enough to overwhelm the Algae Scrubber and cause dark growth.

T5HO Users: This rule has a little bit of a drawback to it for T5HO users. If you are using a stock fixture, this method doesn’t really apply. However, if you are getting yellow rubbery growth, you can back down the photoperiod. However, I would try trimming the screen down first. I did this and the growth got much better. I was running a 20” wide screen and after taking some PAR measurements, I realized that the light in front of the last inch of exposed lamp dropped dramatically, so I just cut that part of the screen off (actually I cut 3” off each side) since I was just getting red turf there anyways and was tired of scrubbing it off. If you are using a DIY T5HO fixture, you might be able to use narrower reflectors and squeeze another lamp in. You lose a little in reflector efficiency, but gain more in additional lamp wattage.

CFLs and Reflectors

The most common CFL used is the 23W Spiral. This is the actual wattage, not the equivalent wattage. There are a few different type of CFL lamps, and each one has a different ideal application. These are: spiral CFL, linear CFL, floodlight CFL.

A bare lamp will work without a reflector, but it will do the job much, much better with one.

Spiral CFL

The spiral CFL is definitely the most common type available and the most widely used. There are 2 ways to orient the lamp: with the end pointing at the screen or with the side facing the screen.

With the end lamp pointing at the screen, a reflector is a must-have piece of equipment. Without a reflector, a lamp pointed directly at the screen will do very little, since a small percentage of the light comes out of the end of the lamp. The cheapest, easiest, and most common reflector for this orientation is the dome-style reflector, which is available just about anywhere.

This reflector provides a wide light signature, since the side light is reflected to the front. They come in several sizes, and you want the biggest reflector you can fit in the space, relative to the size of the screen, that is.

The dome reflector does the job just fine, and one of these should be used at a minimum. However, it is by no means the ‘perfect’ reflector. The reflector has a ribbed, dull surface that does a good job of diffusing the light, but it is not as efficient as a shiny, highly polished spectral reflector. Also, about 1/4 or so of the lamp (depending on the brand) sticks out past the reflector, and most of that light does not get directed toward the screen.

Using several different sized round reflectors can be done also when space is a limiting factor, even though the smaller reflectors are not as effective. This is probably not an issue for very many people anymore due to the new screen sizing guidelines.

With the side of the lamp facing the screen, the reflector is usually a DIY job With a side-style orientation, more light is shed directly to the screen, but you still need to re-direct the light from the sides and back of the lamp towards the screen. There are a few fixtures that you can buy with integral reflectors, but most are very small. Most off-the-shelf light fixtures are for use in a shop or garage and have a half-round solid section, which may or may not have a reflector. If it does not, you can simply line it with aluminum foil or another highly reflective material.

The setup below uses off-the-shelf shop lights. The fixture on the left has reflective material installed.

The advantage to the side-lamp design is that since you can hang the lights from above, they generally take up less space (depending on your reflector) versus the dome reflectors.

In order to spread the light out evenly and wide (but not too wide or you’ll lose intensity at the screen), you want a wide reflector. Finding such a reflector is not easy. Since spiral CFLs can be considered a point source (more of a “blob” source, but this is for simplicity), using an HID reflector can be effective. A DIY beer can reflector can work also. Even some Mylar or aluminum foil will do the job.

Searching for a flexible reflector material and making your own reflector will yield the best results. A properly made reflector for a side-lamp orientation, such as the one shown below, can direct almost 100% of the light toward the screen.

My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote
Old 02-19-2012, 10:11 AM   #40
Aquarium Advice Addict
Floyd R Turbo's Avatar

Join Date: Feb 2009
Location: West Des Moines, Iowa
Posts: 1,682
Linear CFL

Linear CFL lamps are commonly referred to as twin, triple, or quad tube, etc. They are similar in nature to Power Compacts in that the lamp is in a “U” shape, but commonly have an integrated ballast like a CFL. They are usually higher wattage than standard CFLs, are more intense, and can run hotter. However, since they use the screw-in base just like CFLs, they are easy to use and I have recently looked at a couple of nice builds using them, so I thought it was worth adding a section covering them.

Linear CFLs would be installed similar to the sideways spiral CFL, hanging the lamp from above. Reflectors are generally the same principle; however the source is now more linear, so your reflector in turn should follow the line of the lamp and curve around it. Here are a few of the better ideas for this that I’ve seen. One uses cut-up linear fluorescent reflectors, the other uses mirrored acrylic.

A reflector similar to the last one in the spiral CFL section could be done. Because the lamp profile is more linear, the reflector would be slightly different dimensions – probably more square than rectangular.

Floodlight CFL

The floodlight CFL is simply a spiral CFL enclosed in a lamp housing like you would see for a standard incandescent floodlight. They are not very efficient at spreading light when placed in close proximity to the screen, as the light is diffused at the end of the ‘bulb’ and the reflector is of a small diameter. However, they are good for use on smaller, narrower screens – ones that have one dimension less than 6 inches. They should generally not be used for primary lighting, unless you are running a small Algae Scrubber. With the new screen sizing guidelines, the use of these CFLs for quick-and-dirty builds is a little more acceptable, but they are still relatively inefficient, so you will likely need to use more wattage than you normally would.

You can see in this picture that the floodlight only provides significant light to the area directly in front of the lamp – and that’s the only place that’s going to provide adequate filtration:

They can be useful in situations where space is highly restricted, but for larger Algae Scrubbers, more total wattage will likely be required over what would normally be needed.

They can also be helpful to supplement light from dome-reflector setups that just need a little more light but there’s not enough space for another dome.

One thing to remember when handling CFLs: install them gently. Most people are used to twisting in an incandescent lamp tightly. CFLs fracture easily at the base where the element (tube) meets up with the ballast. Cranking on them like causes these fractures. So if you can't grab on to the base to tighten, just get the lamp in there snug enough for the connection to be made. This goes for the lights in your house and office also - it's the #1 reason why CFLs burn out early.

My tanks: 120 Reef w/L2 Algae Scrubber, 60 Reef Pond w/floating Algae Scrubber, 40 Breeder Reef w/L2 UAS Tester Algae Scrubber
I maintain: 144 SW Reef w/L2 Algae Scrubber | 200 SW Reef w/L4 Algae Scrubber
Special knowledge: Algae Scrubbers, Acrylic Fabrication
Floyd R Turbo is offline   Reply With Quote


Please support our sponsors and let them know you heard about them on AquariumAdvice.com

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Algae scrubber for my clownfish fry setup David S Saltwater Reef Aquaria 3 01-11-2012 03:33 AM
Algae Question rdnelson99 Saltwater & Reef - Getting Started 9 08-13-2011 10:12 AM
Coralline Algae = Good Brown Algae = BAD americanbambam Saltwater Fish Only & FOWLR 7 08-08-2011 03:50 PM
Algae problems Ann7667 Freshwater & Brackish - Getting Started 6 07-18-2011 05:15 PM
Essentially Algae Free Tanks BBradbury Show Off/Photography 3 07-04-2011 04:46 PM

» Photo Contest Winners

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2012 Social Knowledge, LLC All Rights Reserved.

All times are GMT -4. The time now is 01:37 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.