LED Light for 36" High Tank

[Hoppy]

With a lot of reluctance I agreed to build a LED light for one of our members, for his 36 inch high, 43 inch long tank. Since I won't have to pay for it () I can use higher quality LEDs and good LED drivers, etc. I now have most of the parts, just being short on LEDs, so I have started building it. Here is what I think will work:








I would welcome any suggestions, comments, etc. that might prevent me from ending up with egg on my face!

[Rockhoe14er]

wow. lucky member. I can't wait to see this build.

[Hoppy]

The goals were:
Get 40-50 mms of PAR, for sure, with good probability of being able to get twice that.
Moonlights.
Hanging no more than 20 inches above the top of the tank.
Good coverage of the whole tank.
Some shimmer effect, if possible.
No fans, if possible.

I believe I can meet all of those requirements, and have the ability to do some limited adjustment of the color temperature too.

The parts cost? So far it is:


I have my fingers crossed as to whether I will make a profit on this.

[O2surplus]

It looks good to me- Hoppy. I think that you'll get close to twice the PAR you're aiming for.

[Hoppy]

It's amazing what you can do, at least in theory, with optics on LEDs. I plan to calibrate the light so it is possible to dial in the PAR you want - any combination of the two colors of LEDs. The only problem I see with that is that so much of the light will be reflected off the glass, that my in-air calibration could be 20% or so low. That is still pretty good - aim for 50 mms of PAR and get 60 in water.

As I see it, the biggest problem with lighting a 36 inch high tank is the huge range of PAR values from substrate height to the top of the water. Raising the fixture a foot helps with that, but raising it 3 feet would have helped a lot more. I'm thinking that the next iteration on obtaining the "best" light will be when we can get a light that keeps the PAR within +/- 20% from top of tank to bottom of tank.

[O2surplus]

Hoppy, you've got a solid design-I wouldn't lose any sleep over the PAR level variations. Plants seem to be pretty adaptable to varying amounts of light from what I've seen in my own tank. I've got JAVA FERN that is thriving, and is growing directly under my led rig. The ferns are only 10" down from the lights, and a complete carpet of Glossostigma is spreading like crazy at the substrate 34" down. According to every aquatic plant book that I've ever read, this should not be possible. I guess- no one ever told my ferns about their low light requirements, HeHeHe.

[audioaficionado]

As his plants grow taller, some of that glass reflections to the substrate will be absorbed. Too much light is better than not enough as you can dim it at first and raise it as the plants grow in. Very nice plan for the rest of us DIY LED guys to model from.

[sns26]

If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.

What are you going to use to drive the moonlights?

[IWANNAGOFAST]

Originally Posted by sns26

If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.

What are you going to use to drive the moonlights?

I have 24 XP-g over the same size tank, even at 30" from substrate it's high light.

[Hoppy]

Originally Posted by sns26

If your calculations are right, then my own array (27 mostly XP-Gs over a 36"x18"x20"h tank) is going to be a fryalator, not a light source. But I knew from the start that I might be going overboard.

What are you going to use to drive the moonlights?

I'm hoping that with 1300 mAmps the light will be high light, so when dimmed, and the color adjusted, it will be 40-50 mms of PAR. The 3 moonlight LEDs will have their own 350 mAmp driver, not adjustable, but also not very bright at that distance, with 60 degree optics. I think I would leave the moonlights running along with the other LEDs, to add some blue for better color in the fish.

I have the heatsink and aluminum channels screwed together now. I used a flat sanding block to flatten the mating surfaces, and used some heatsink grease between them for better heat transfer. Now, I'm struggling with installing the hanging kit, from RapidLed - as they noted, it doesn't fit well between fins on the heatsink I have. It only lacks about 1/32 inch of making it, so a small rotary file should make room.

[bryfox86]

Subscribed! thinking about doing either LED or a DIY MH/CFL (ADA Style) for my 150 cant wait.

[Hoppy]

Originally Posted by bryfox86

Subscribed! thinking about doing either LED or a DIY MH/CFL (ADA Style) for my 150 cant wait.

A pure LED light is much better than any alternative, if you can swing the cost. And, DIY LED lights can be whatever you want them to be - the available LEDs today can do just about anything you would want on a planted tank. DIY reduces the cost down to be competitive with most non-LED lights.

[Hoppy]

I finally got the hanging kit installed, using aluminum spacers to make it fit.



From the LED side, you can see the screws holding the channel extrusions to the heatsink, and the connector that will bring in the power to the LEDs. Later today I expect to add the wires to the connector, in preparation for getting the LEDs - some day?

[Rockhoe14er]

Where did you find those aluminum pieces that you attached to the heat sink? also did you have to cut the aluminum?

[audioaficionado]

Looks like Hoopy just bonded two C channels onto the main heat sink.