High-Power LED Fixture for a Planted Tank

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BigJim

Aquarium Advice Addict
Joined
Jul 8, 2009
Messages
4,388
Location
Oak Forest, IL
I've wanted to try a high-light planted tank for a while, but I needed to upgrade my lighting first. After looking at lighting options, I really wanted LEDs. I like the idea of not replacing bulbs, but I wasn't prepared to spend a couple hundred dollars on a light fixture for a small tank. I decided to attempt to build my own LED fixture.

My design process:
I really didn't know much about LEDs. I had no idea how they compared to T5HO bulbs or even what LEDs I needed to use. I tried comparing LEDs to T5HO bulbs using lumens, but got nowhere with that. LEDs and fluorescent bulbs are too different. I found PAR is a better comparison metric, but it's difficult to find any PAR readings.

I found a rather comprehensive explanation of lighting here: Aquarium Lighting; Kelvin, Nanometers, PAR, Bulb, Watt, MH, LED, Light Basics. The link has been edited, but there's a ton of information I also found some pretty good information reading through reef forums. This thread, DIY LEDs - The write-up - Reef Central Online Community, finally gave me the information I was looking for: How LEDs compare to T5HO bulbs using PAR measurements. Turns out LEDs beat the T5HO PARwise, so I was sold. I started looking at Cree LEDs and I settled on the Cree XR-E Q5 LEDs.

Cooling the LEDs was my next challenge. The diodes aren't cheap and I'd hate to burn them out because of inadequate cooling. Heat sinks are blasted expensive, so I was hung up there for a while. After seeing fixtures made out of plain aluminum, I decided I'd try building mine out of aluminum and hope for the best with water cooling as a backup option.

Parts list:
10 Cree XR-E Q5 LEDs - DealExtreme: $5.09 Cree XR-E Q5 Emitter on Premium Star (228LM at 1A)
LED driver - DealExtreme: $10.70 2000mA 30W Power Constant Current Source LED Driver (85~265V)
Aluminum project box - Radio Shack
Switch - Radio Shack
DC power connectors - Radio Shack
Potentiometer - Radio Shack
Resistor - Radio Shack
1" square x 1/16" thick aluminum tube - Home Depot
3/4" x 1/8" aluminum bar - Home Depot
3/4" x 1/16" thick aluminum L-channel - Home Depot
1/2" 8-32 machine screws - Home Depot
8-32 nuts - Home Depot
16 gauge? wire - Home Depot
Heat sink compound - eBay
1/4" washers - my garage
AC power connector and cord - old computer power supply

Tools:
Ruler
Permanent Marker
Hack saw
Center punch
Drill
Drill bit index
8-32 tap
Crescent wrench
Screwdriver
Soldering iron

I didn't want any evidence if the project turned into a pile of smoking wreckage, so I've only got pictures of the finished product.

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Inside the project box is the LED driver. It takes in AC line voltage and converts it to 2000mA 16-18VDC constant current. The switch simply switches one of the legs of the AC input. The third pin is grounded to the chassis.

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On this side of the box, you can see the DC power connector and the dimming control knob. The power connector is just a nice clean way to transfer the power through the box wall. I found instructions for making the LED driver dimmable on DealExtreme where I bought the driver. It was actually pretty simple to do. All it took was a resistor and a potentiometer. I made the mistake of using an audio pot instead of a linear pot, so the dimming control isn't very good. The LEDs really don't start dimming until the last quarter of the pot's travel.

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Here you can see the LEDs all lit up. Each leg of five LEDs is wired in series and the two legs are wired together in parallel. At full brightness, each leg is using 1A of 18V power. The wiring is a little sloppy and I may clean it up or at least use some wire ties. I think I'd try to route the wires through the frame on my next fixture.
 
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Here's a feature I was rather proud of. The legs of the fixture make a 4-bar linkage. I can rock the fixture back out of the way so I can open the lid, but I can rock it forward to illuminate the the front half of the tank. Unfortunately, I didn't take the thickness of the tubing into account, so it hits the filter.

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Here's a shot of the tank with the LEDs at about 2/3 power on my 20H. The pictures don't do the lights justice. I nearly blinded myself the first time I turned the LEDs on and only 7 of them lit because of a short. The aluminum gets warm to the touch, maybe 90 degrees, in my 68 degree basement, so I don't think I need any more heat sinking. I'll reevaluate in the summer when it's hot out.

I figure I've got about $100 invested in the light, not including tools, $50 of which is in the LEDs and driver. I probably could have saved a few bucks by ordering all the components together, but I didn't really know what I was doing, so I had to buy as I went.

I'm currently running the LEDs at about 2/3 power because I don't have CO2 or dry ferts yet. It's still brighter than the 36W of T5 light I had on the tank previously. If all goes as planned, I'm hoping to see some better growth out of my plants. I've got a few sprigs of asian ambulia that's been hanging on, but not growing well. If those come back, I'll know I've succeeded. I'll try to follow up in a couple months with some plant pictures.

Feel free to ask questions or PM me. I tried to spare you some the boring details, but I'll be happy to share if you really want to know.
 
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Very nice. I would think the aluminum bar would act as a pretty good heat sink. Do you think you will have to go water cooled at all?

So all said and done, do you have a cost estimate? And what do you think would be a comparable (watts-wise) T5HO fixture based on what you learned about PAR?

How about color temp of the LED light? I am guessing somewhere around 8000-10000K?

Anxious to see this thing grow some plants! It doesn't seem that long ago that the LED fixtures for planted tanks were a distant thought, but we are really seeing an explosion here on planted tanks as of late. Exciting stuff.
 
Sorry, had to split into two posts for pictures. I included more information above.

I don't think I have to water cool. I may need some finned heat sinks during the summer, but I'll wait and see.

The LEDs are 6500K - 10000K. The tank looks very similar to the daylight spectrum and ColorMax T5 bulbs I had on it before, just brighter.
 
Wow it really looks bright. For your first, I think it looks really good.

I think for the next one, I would try and use a " |_._| " shaped bar and mount the led's/wiring inside so that it shields the LED, and hides the wire (if my ASCII pic makes sense :) ). But, I am also a little rediculous when it comes to the aesthetics :).

I like the psu box you enclosed it in, and the pot is cool. Nice to pretty much be able to dial in whatever light you want. Now to get some electrically controlled pots and simulate sunrise and sunset ;) .

Good work BigJim! What kind of engineer are you by the way?
 
I think I've got what you're saying. I looked at U-channel, but I thought the stuff Home Depot had would block too much of the LED's spread. If I had a Bridgeport, I'd probably have gone that route, but I don't. I think next time I'm going to try threading the wires through the square tube, or if I get crazy, I might try a circuit board.

That's just an aluminum project box from Radio Shack. The LED driver isn't encased, so I needed something.

The sunrise/sunset and moon phase capability is actually in my plans for the next fixture. I just have to learn how to program ICs in my spare time. I'd actually like to make the moon lights at least move across the "sky" in addition to rising, setting, and phasing. I think I can actually possibly retrofit my current LED driver with an IC and a transistor using PWM control for the sunrise/sunset effect.

I'm a mechanical engineer. BSME from The Ohio State University June 2008.
 
It's been two days and I've got a fine film of algae on the glass already. These LEDs are definitely more powerful than the T5 fixture I had on the tank before.

I blew my spending money at the fishing show last weekend, so it might be another week before I can buy the ferts I need. Guess I'll have to turn down the LEDs some more.
 
Dang. Any plans for CO2? It could help significantly with the algae...
 
I'm going to put a CO2 tank on my birthday list. I asked for one for Christmas, but no one really know what it was. I've already got a regulator so once I have the tank, I should be good. I'll turn down the LEDs and make due until my birthday in March.
 
Do you ever run your LEDs at full power? If the heat becomes an issue I have seen some people use positive pressure fans to move air through the square aluminum. stevesleds.com has a few he uses that same material as heatsink for his led setups he sells. I am doing a much smaller LED light for a 3gallon picotope planted tank.
 
I've run the LEDs at full power just to check how hot the fixture got. I'd like to avoid using fans if I can. Fans would mean I need another power supply and small fans make a lot of noise because they need to run at high RPM to move any air.

I'd rather add some heat sinks to the fixture or try a water cooling setup instead of fans. I contemplated doing water cooling from the start. I was going to use a small powerhead and some tubing and pump tank water through the fixture. It could still be done pretty easily, but I need to find some aquarium-safe tubing that transfers heat well.

I also thought about using thermal epoxy instead of screws to fasten my LEDs to the frame and running water directly through the aluminum frame. Apparently aluminum can be toxic in an aquarium, so I scratched that idea too.

Right now I've got the LEDs running at 1/3-1/2 power. I don't have CO2 or ferts yet and I've got green spot algae all over the glass, so I had to turn them down further. Once I've got all the gear I need, I'd like to crank the LEDs all the way up and see what happens. I think a high-light jungle tank running on ~30W of light would a pretty good accomplishment.
 
Fully cranked that would be more than highlight lol. I have seen a few people try the water cooling methods on some Reef led setups they have to use stainless or titanium which both are way spendy. I run my fans at about 9 volts and they are silent you would be suprised how very litte air movement you need. On my 36 the light bar for my actinics sits right next to my halides. there are 10 royal blue crees on the heatsink without active cooling I get to about 110 on the heat sink measured with an arduino, with the fans on (two small computer fans super cheap) at 9 volts they are silent but can cool the heatsink down to a balmy 84 without any problems and thats sitting right next to my halide reflector which can boil water.

Water cooling with tank water could be an issue too I would suspect that the temp swing after the light went out wouldnt be all that fun for your fish.

It sounds like a great idea if you could implement it I would love to see. Do you have glass on top of the tank? I didnt see a splash gaurd on the emmiters.
 
I would run a heater in conjunction with the LED water cooling. When the LEDs shut off, the heater should be able to pick up the slack. I just figure that I'm making heat so I may as well use it.

I've got a glass canopy on the tank. I don't really like the idea of an open tank. I'm afraid I'd have jumpers.
 
Fort sent me some Glossostigma Elatinoides and Rotala Wallichii which I finally got planted yesterday. These, along with a few surviving sprigs of Asian Ambulia, are my only high-light plants and will be a true test of the capability of this light fixture.

I did a 50% PWC last night (got distracted while draining) and dosed maybe 2/3 of a capful of Flourish. This morning the plants were actually pearling! I thought the rotala might have just caught a few bubbles when I was refilling the tank, but the water sprite and even the glosso were pearling also. I wish I had had time to get a picture, but I had to go to work. Gotta pay for a new rear axle and four wheels for my wife's Jeep.

I ordered some dry ferts last night so I can start dosing the tank the right way. I think I'm going to try the PPS Pro method.
 
Very nice design! I would like to make a fixture similar to yours for my 180 gallon. I'm looking for low to medium light so i think I would space mine similar to yours and run two rows. I'm guessing I would need 3 drivers for 3x as many LEDs? or would I be better off getting a larger driver? I'm trying to spend as little as possible and I'm not really good at picking out the quality products on DX lol. Any help would be aprreciated. thanks!
 
If I were aiming for low to medium light on a large tank, I would look at 1W LEDs instead of the 3W diodes I used. You'll get better coverage for the same wattage.

You'd have to do the electrical calculations to figure out what driver would work best for you. I picked the driver I did because it would allow me to run my fixture with two parallel legs of five LEDs in series. Running more LEDs in series would require more voltage, but the same amperage. Adding another leg of five LEDs would require another amp of power at the same voltage. If you're not familiar with basic electronics, do some reading before you attempt something like this. Getting shocked (or worse) isn't any fun.
 
I ordered some dry ferts last night so I can start dosing the tank the right way. I think I'm going to try the PPS Pro method.

I am switching from EI to PPS Pro so I can use an autodoser. I am currently pricing out the components and using neilan's plans (http://www.aquariumadvice.com/forums/f20/diy-auto-dosing-solution-101464.html).

I had good luck with EI but I get swamped at work in the summer and take long vacations so I figured something automatic would be good to start thinking about.

I am probably going to start a build thread once I get the components picked out. I can shoot you a PM when I get it posted, if you are interested.
 
I built some autodosers using those plans with only a couple of slight modifications. So far it is working out great.
 
Interested. I have a friend that owns a mh cooling campany and he says leds cant grow plants long term. I believe that anything is possible. So following just to bust his nay saying butt.
 
The autodoser plans look good. I've seen a few ideas including one that uses a syringe, two check valves, and a lamp timer to mechanically drive the syringe. I may try the autodoser eventually.

I've seen people use the same LEDs I used on reef tanks with good results over a year. Corals are much more demanding than plants when it comes to light. I've also seen planted tanks using LEDs that have been running for a year and they're healthy too. I think ultimately LEDs will replace filament bulbs in most applications. LEDs are ideal for aquariums because they're directional sources, so you don't have to use reflectors to get the light into the tank.
 
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