mike8333, I played around with a few formulas including the lumen comparison you mentioned. I got similar ridiculous numbers when trying to match the output of T5HO bulbs. I finally decided I couldn't calculate what I needed very well, so I decided to try ten based on other fixtures I saw and ten is where I got a price break on the LEDs. Pretty arbitrary, but it worked for me. For clarification, I've been running the LEDs at full power since I added the CO2
system. For your tank, I think I'd start as simply as multiplying my setup (24" tank) by 2.5 for a total of 25 LEDs over your 5ft tank. You may be able to get away with fewer.
Bud, thanks. I've still been really busy, so no new pictures. I need to tweak the nutrients anyways, so the plants aren't at their peak. I'm hoping to do another fancier LED
build in the next few months.