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Semi-DIY LED Hanging Lights for 45 Tall

2583 Views 6 Replies 3 Participants Last post by  smj, 
smj
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I've been slowly getting ready for a new (to me) 45G tall tank in my living room (journal here). I learned from a 15G Tall the importance of getting light through the water column, and was bummed at the cost of decent lighting for what's been a pretty cheap (in dollars, if not time) build. Then I noticed a number of 30-50W 6500K LED floodlights or worklights listed on eBay :icon_idea ...

I began looking at where the tank was going to be, finding out where the joists were in the ceiling, and ordered a light to check out. At $16 or so it seemed hard to beat, and it kept putting out consistent light over a few days so I ordered a second one - the first light seemed strong enough that two should do it. There are also dimmable RGB versions, but I haven't taken a look at those yet.

With both lights running, most of the time the Kill-a-Watt indicates they draw 45-50W total. I know I need to measure PAR to see what the plants want, but I haven't converted this light meter yet. Using it, with the light rig hanging 26" above the stand, I measure 2,500 lumens dead center and front-center; 2,000 lumens at center-rear because I have the lights offset slightly to the front; 1,500 lumens at the center of the left edge and 1,400 on the right. Corners vary from 1,300 to 1,600.

There's space to fit an additional light, which may one day be an RGB unit if I can figure out how to control that as a sunrise/sunset light. These lights are all wired for 120VAC, so controlling the RGB unit might involve having an Arduino impersonate the IR remote control rather than tearing them all down.

Here's a picture of the prototype hanging, tank is visible on the left. If you want to see some of the steps in creating the fixture, have a look at this album on Flickr.

Bump: One more picture - I used a jigsaw to cut the holes, and a router to create a "well" that will help keep the lights in place even when the fixture gets knocked around. There's space to one side for consolidating the 120VAC power lines, or to mount a controller of some kind.

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smj
The 30W GLW-brand units I used are fixed, 6500K daylight white lights. But there are also RGB versions, and I thought I might use one of those for the third light. I'm not sure that's a great choice now that I've had a look at a 50W unit...

If you're running a pure primary color, the rated output will be a third or less of the total output - fine. But the color combinations supported are very limited, and while a fade function is mentioned I couldn't get the unit to do it. Setting it to "white" gets you something mostly blue. Maybe it could be rewired to an Arduino for better results, but maybe not - and you might be better off building up from components at that point.

I might just add a third 6500K instead. The two lights seem to be giving decent medium light, and the staurogyne is staying low in the front corners. But I think the dwarf hairgrass could use more light to help it fill in front and center, and I'd like to give it a better chance...
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Maryland Guppy
smj said:
With both lights running, most of the time the Kill-a-Watt indicates they draw 45-50W total. I know I need to measure PAR to see what the plants want, but I haven't converted this light meter yet. Using it, with the light rig hanging 26" above the stand, I measure 2,500 lumens dead center and front-center;
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How hot do these get, the look reminds me of the 500watt quartz lamps.
Caught lots of stuff on fire with them accidentally back in the day.

Compared to some PAR reading for my pucks 2500 lumens was bringing about 65 PAR on combination pucks.
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smj
Maryland Guppy said:
How hot do these get, the look reminds me of the 500watt quartz lamps.
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Warm to the touch, no more. The heat sink appears to do a good job.
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andiok
hey smj.
smart build.
did you have a chance to test the PAR of your fixture.
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smj
Sorry, still haven't converted that meter to measure PAR. But the three 6500K light combo has been doing a pretty good job for me. My problem is that I like to keep large duck weed around, and if it gets out of hand - say, you get a new job and aren't around so much any more - it can start blocking a lot of the light. But that's a different matter.

Light seemed to be keeping the dwarf hairgrass in the center/front happy enough, but maybe not as much light as the staurogyne would like as it tends to get leggy.
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smj
Small update - about a year later, two of the three lights had crapped out. Replacements are under $20 on Amazon, shipped "free" under Prime, so I haven't bothered taking apart the failed units, just bought replacements. At least one of these lights should have fallen under the 1 year warranty, but I was busy and didn't bother with that either.

$40/year might be asking a bit much from the maintenance budget. but the rig is built so I'll stick with it for now.
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