A few months ago I completely drained my 80 gallon tank to make it a dirt tank and decided it was a good time to swap the lights out too. I had been using a DIY light hood with 4 T5HO bulbs that were run using the kits that are sold by AH Hobby Supply. Here's a picture of the tank and stand for reference – the lighting is terrible, but it's just after I brought my homemade stand/hood in after the final coat of urethane.
I ran the tank for about a year with high light, CO2, EI ferts and the plants grew like crazy, but it was a LOT of work. Moving to dirt my goal was to build an LED light that was capable of providing an even PAR spread and could provide low to high light in my tank. Basically, one light that would let me do whatever I wanted in the tank.
I was inspired by some other builds on this forum:
I settled on 6 Bridgelex Vero 18's as the primary light source, with some 430nm violet LED's thrown in. I'm not sure this makes any difference or not, but its the only wavelength of light that was not covered by the Vero's, so I added them for the heck of it. I chose to use three 5600K Vero Decor COBs and three 2700K Vero Decor COBs. There are COBs with higher lumen output, but I chose these for their higher CRI (90+). The spectral plot for the COBs is shown below, I think it does a good job of hitting most of the photosynthetic spectrum.
The 430nm LED probably weren't needed, but I added 8 of the small stars from Steve's LED's.
For a heat sink I used a 3ft MakersHeatsink. It was pricey, but it is a MASSIVE piece of metal. Seriously, I wasn't prepared for how much aluminum that thing is. It's very nicely designed and has T channels so it's easy to install the LED's. The only downside is that the cooling fans it comes with are terribly loud. I replaced these with some high quality near silent Noctua fans and the light runs near silent and the heat sink is cool to the touch anywhere I can touch it.
The tricky part about the Vero's is that their forward voltage is high ~30V according to the data sheet. So I had to power the light using a 48V Meanwell power supply capable of ~7.3A and each COB would require it's own driver. I went with 1000mA drivers for the COBs and a 700mA driver for my 8 violet LEDs. I used the 5 position Coralux boards to house all the Meanwell LED drivers that I used in the project. I went with the PWM dimmable drivers as I already had my own DIY AVR based controller on the tank.
Parts where purchased from DigiKey, Steve's LEDs, and LED Group Buy. A near complete build of materials is here:
5600K Vero 18 (BXRC-56G4000-F-24) x 3
2700K Vero 18 (BXRC-27H4000-F-23) x 3
LED Group Buy
Meanwell nes-350-48 - 350w 48v dc power supply x 1
Coralux 5up ldd driver board x 2
makersled designer heatsink kit 3ft x 1
Violet LEDs x 8
Meanwell LDD-1000H Driver x 6
Meanwell LDD-700H Driver x 1
Noctua NF-A9x14 PWM 92x92x14mm 4-pin PWM 300-2200rpm SSO2 Bearing x 3
Plus several feet of misc wire that I already had lying around the house. The total cost was around $450. Given the amount of light this thing can push out, I do think I saved a little money over buying high quality LED lights from a vendor. What it really gained me was a light that was very easy to control all aspects of the intensity with. I can ramp the 2700k Vero's up in the morning for a great sunrise effect, similarly, the 5600k's do the same for the moon. That's a lot of typing, how about some pictures of the light and tank after 3 months!
This shows the layout pf the parts in the hood. The power supply is in the back along with a 12V supply for the cooling fans. I wish I caught the Coralux driver boards in this pic, they are mounted inside the hood just off the left edge of the pic, you can see the wires coming from them. The actual controller is mounted in a box in the aquarium stand – it also controls my CO2 and some protective relays for the tank.
An underexposed shot so you can see the part layout and wiring on the heatsink.
Now a few shots of the tank. I run it at medium light ~50PAR at the substrate with CO2, but no additional water column fertilization.
I'm really happy with the way the project turned out. It was a lot of work and I was surprised how hard it was to solder the LED stars. I think this was because they were mounted to the heat sink already, so I had to crank my iron up to 800 degF to get the pads hot enough to take solder. The light will provide 175-200 PAR at my substrate if I run at full power and I can run it down to about 5 PAR, so I achieved my goal of building a light for this tank that will let me do anything I could every imagine. Since the Vero's have a 120 beam angle, the PAR in the tank is very uniform and I get the shimmer from the LEDs! I do wonder if I could have cut the design down to 4 Vero's with some violet LED's. Might have let me get away with either a 2ft heat sink or 2 smaller heat sinks and less LED's. Such a build might only do medium to medium high light, but could be done for nearly $100 less money. Hopefully this helps some folks out with information and encourages some more DIY builds. It really is a fun process.