Algae Scrubber Basics

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The slot is just thick enough to fit the screen in without to much difficulty . I used a dremel cutting wheel . Yes it is fed from one half of my overflow . The water is even across the screen and the full screen is getting wet . It only burps out at the end of the screen. I attached a video when I pan to the left side or the end of the screen I pause . If you look at the top left you will see it burp out of there. I can get exact thickness of everything after work.Thanks

Your flow is way, way too low. In the video it's just dribbling off the screen. That's problem #1 that I see, that's what is causing the streaking also.

As far as the bubble, it looks more like the water is dripping off in that area, could be that the pipe is not level and as the water builds up a little then it pools and runs out in that area. Adding a gasket around the pipe will stop it from 'escaping' but I think you have bigger problems:

You want 35 GPH per inch of screen width, basically a sheet of water running down both sides of the screen, covering the entire screen, and you should have a solid sheet of water coming off the bottom of the screen.

I can't tell from the video, but you need to realy rough that screen up if it is not already, or else it won't hold algae very well.

Also review the summary posts starting with #33. I haven't looked at your tank setup, but your screen appears to be vastly oversized. The new feeding guideline is 12 sq in of screen for each cube of food fed per day. Your screen looks like it is something like 16" wide and 12" tall which is large enough (if working right) for 16 cubes of food per day. Unless you're feeding at least half of that, and unless it's lit properly with the right flow and screen roughness, it'll never work quite right.

Bigger is not better when it comes to scrubbers. Size according to feeding, get your flow and roughness right, and provide at least 1W per sq in of screen (LxW) and as much as 2W (split between each side).

Example if you feed 2 cubes/day then you want 24 sq in of screen (4x6) with minimum 12W on each side, or as much as 24W on each side.

If you have the higher wattage, you can run the lights less hours as long as you have a mature screen and all of the light hits the screen (good reflectors or LEDs)
Ok first thank you for the detailed responses you are most helpful. The screen is 18 by 12 and it is very rough I made sure I was only doing that once. It is a 180 gallon with a porc puffer , emperor angel and zebra lion . The puffer is the main reason I made the screen so big since he is a eating machine. I will review the posts you mentioned and hopefully something jumps out at me. It probably has something to do with my slot pipe I would guess. Thanks
Adjusted the slot and diverted flow from my overflow to get more flow. 3/4 look good to me the rest of it not so much. Do I still need more flow to get the other part of the screen or is it something else . Thanks.
It looks a little better but you really want the water sheeting down the entire screen.

If you can, try to ballpark what you are actually feeding on a daily basis over an average week. Then re-size your screen accordingly. You can probably oversize by about 25% if you want a little safety factor, but don't go over that. And the amount of lighting and the way you do it is also very important. If you can, post a few pics of the overall setup including the lighting, or describe as much as you can.
Ok I will have to do a bunch of figuring on the food so I will get to that ASAP. I have two clamp lamps on each side with the cfl bulbs from home depot that you have posted a pic of a few pages back. The overflow is a CPR 1200 gph . One pipe feeds my skimmer section the other I turned into the scrubber. The return pump is 950 gph ( I could get a stronger one giving me more flow if needed) . Here are pics of the setup. I am going to replumb the section between the slot pipe and overflow with less bends to try to squeeze some more gph to the scrubber


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Ok I'll try to make a stand of sorts to get them where they need to be . Is two lamps enough or do I need 2 more?
Is this better? There is one on each side. Thanks sooo much Floyd .


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Bigger is not better when it comes to scrubbers. Size according to feeding, get your flow and roughness right, and provide at least 1W per sq in of screen (LxW) and as much as 2W (split between each side).

Smaller is better, but not too small. Right? 1 cube is 12sq inches. Ok to do 10 or perhaps even 8sq inches per cube? (not crazy small like 2 or 4 sq inches).
Is this better? There is one on each side. Thanks sooo much Floyd .

Better than it was. Since your screen is really down in the sump, that makes it a little tricky to light it properly. You really want the light closer, like 3 or 4 inches, basically as close as you can get without burning the algae.

Smaller is better, but not too small. Right? 1 cube is 12sq inches. Ok to do 10 or perhaps even 8sq inches per cube? (not crazy small like 2 or 4 sq inches).

You can technically go as small as you want, and for some nanos, this works well. But if you have the space for it, I would go 12sq in minimum
Ok thanks floyd . The whole screen is green and growing daily . I might add another light per side I'm just seeing how it grows and will readjust if needed .
I don't understand the amount of LED needed for one 12sq inch screen, lite on both side for 1 cube of feeding (120g with 40g sump FW system). There is also something written about cooling fans + LED. Why is it important for LED?

How do I build a LED for my unit? The screen will be around 3x4inches. The choices of stock lighting seems limited due to my small screen, so I'd thought I could build one. The ATS will be located under my stand, hanging above my sump. I read something about moisture damage. I do not think I will have that problem since my stand has an open back.

I have been looking up "led grow lamp 660".

Edit: do you happen to know the best way to make a ATS that could be removed if needed? I think this guy's ATS is ideal, but wanted to know if there is a better way to do it easily: (scroll down to his last few posts)

EDIT: I found your main stomping ground at I understand now. I'll try to test around with different LED lights.
I have been seriously considering building a scrubber recently but really don't know where to start.

If I can get rid of my skimmer, I will have more than enough room if I make a system that has its own pump feeding the screen. I'm worried about having the drain get clogged and causing my system to overflow which is why I was thinking about a self contained system.

I'm pretty sure I would only be able to have light on one side. From what I'm reading, I would need a screen the size of about 4x6" since I'm only lighting one side. I will be using 6500 temp bulb with a cheap reflector.

Any ideas on the pump to use? I've seen a setup where they used a pump to feed water into a PVC pipe stand shaped like an upside down U with feet. The screen would sit in the middle. I have no idea what kind of pump to use. I know 35 GPH but that seems really low. I think my drain right now is 600 GPM (it is a 1 1/4" drain).

The other idea is to have a split drain with ball valved to adjust the flow into the sump but that just complicates things. With a split drain I can limit the flow down the screen and have a split before or after the screen for the rest of the water.


EDIT: I didn't see before that it was 35gph per inch of width. That makes more sense.
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For a 6" wide screen I would use the Eheim Compact 1000 pump, $33 on BRS or Marine Depot. I recently tested that and the Cobalt MJ-1200, at 13" of head the Eheim puts out ~200-205 GPH, Cobalt about 180-185.

As far as feeding from the drain and splitting it, you can do that but you're right it's a pain, plus you would really want some kind of secondary bypass protection in case a snail or something made it to the slot pipe and clogged it, and 2 valves, one for tuning the flow to the scrubber and one to shut the flow off during maintenance (so you wouldn't have to find that sweet spot of flow every time)

I like the Eheim pump because it is cool and quiet.

Not sure what you're talking about with the upside down U PVC pipe, are you talking about the slot pipe? See the summary in this thread starting with Post #33, if you haven't already read it...
Is this scrubber doing well?? Made it about 3 weeks ago and changed the screen to be more roughed up about 2.5 weeks. First cleaning.


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Nice growth for a couple of weeks!

In the 3rd pic it looks like you had a couple of large sections that detached from the screen. I'm guessing that this is before you roughed it up? Also, the growth looks pretty thick and heavy, which is good for scrubbing but that much growth blocks the light to the lower layers, causing the roots to die and this may have been what led to detachment. This also leads to yellow water. So you definitely need to clean every 7 days. You could go longer if the screen was in a box that allowed for 3D growth, or possibly if you draped the screen in saran wrap.

What did you use to rough up the screen, and are these pics after that or before?

When the holes are filled in, and algae stays in them when you scrape it, then it's mature. If not, be careful how well you clean it - you want to leave the algae in the holes. Don't use a sprayer to clean it, just scrape and rinse under room temp tap water and scrub the edge that goes in the slot (as clean as you can get it) as well as the slot itself...if you didn't know that already (or anyone else is wondering about that)
That's after. I think it fell off because it got too thick. I will scrape every 7 days but I didn't know that before so it probably caused roots to die.
I'm going to make one of my remote refuge that is gravity feed from tank to refuge to ALGEA scrubber but I'll use a huge PVC tube cut in like half with the screen suspended like a half inch off the surface (depending on running level) and that way no addition pumps are needed will polish water as it comes outa the refuge also
Why do you always spell algae ALGEA in caps?? Kinda weird to ask here but I find it funny haha. Your plan sounds good.
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