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post #5 of (permalink) Old 12-30-2012, 03:21 PM
Algae Grower
Join Date: Jun 2007
Location: River Falls, WI
Posts: 34
Here's a thread...

which includes a calculator.

One Way to Design a Planted Tank LED Light

Here's a build link for a 72" full spectrum reef light, using ocean coral whites (mentioned below), way more light than you'll need for planted:

For your build, assuming your lights are 36" off the substrate and 60 degree optics, 80 XM-L's will give you 400 PAR when turned up to maximum. That's way too much for what's generally needed for a freshwater planted tank.

30 will give you a more reasonable 100 PAR, which is still high light, good if you can turn it down. And you should turn it down if you have all the other LED's running.

The 430 and 660 nm light will add to PAR. The 405 should, if I've been reading my literature correctly, help with the development of plants blues and reds (anthocyanins are formed in reaction to near-UV). I think you're way too high on the number of red LED's too.

Your mix may look a purplish with all the blue and red, you might want to add a little green to balance to white. Or just go with the 3-up Ocean Coral White LED's which have blue, teal, and red to make white. Then you can run your colors in conjunction with the XML-s during the day (and maybe cut down on them further).

Why green? Viewing. It helps to balance the blues and reds you're adding for photosynthesis so that the light isn't purple. It will help your leaves "pop", not to mention - what would a neon tetra look like without any blue/teal light to diffract off its stripe?

Not sure what you mean by

theyll be in 30 cnt strings
10/20 cw/dr (m2) ch3
10/20 cw/rb (m1) ch2
15/15 tv/hv (n) ch4
60 cw (d) ch1
since all of the LED's you're using have different current requirements. You don't want to put 30 LED's in the same string, you'll have a total forward voltage of approx. 100 V (too high). You can't wire that voltage drop in one string (that's a lethal voltage). Parallel strings is a PITA if you know what you're doing and a recipe for blown LED's if you don't.

You can't put an XM-L and a 660nm LED in the same string (easily), and I'm not sure there's a driver around that will drive 30 XM-L's all on its own. 300 watts! Each different type of LED will need to have its own driver, and you'll need more than one driver for some.

My planned build which I'm not close to starting yet will have about 20-30 XML's, neutral and warm, about a dozen violets (405-430), with maybe 6 green and 3-6 red, for a 72" x 24" x 30" high 200 gallon. I'll need 2-3 drivers for the XML's (max current 3000 mA), one to two for the blues and violets (max current 500 mA), and another for the greens and reds (max current 500 mA) if I can get them in the same string.
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