LED builds and calculator don't add up

[sklywag]

Thinking of doing an LED build seeing some of the new posts and crazy green growth.
According to the calculator. A 1 cube a day scrubber only needs 2-3 watt LEDs per side. But everyone is running more than that. What gives? I'm looking at these kits and thinking either one should be enough for a 1 cube a day tank.
http://www.ebay.com/itm/6x3-W-LED-With-Constant-Current-Driver-Kit-DIY-item-/120816481692?pt=LH_DefaultDomain_0&hash=item1c2139359c
http://www.ebay.com/itm/8x3-W-LED-With-Constant-Current-Driver-Kit-DIY-item-/120817059365?pt=LH_DefaultDomain_0&hash=item1c21420625

[SantaMonica]

My HOG1 scrubber is 6 watts, and grows great unless the nutrients are high, in which case the HOG1x with 12 watts works better.

[sklywag]

So you think if I get the 8 LED kit for a screen that's about 7x7 would be fine with four on each side?

[SantaMonica]

It's a good start, just not the most powerful.

[Floyd R Turbo]

I started the guideline and said originally 1 3W 660nm Deep Red on each side of each 4x4 section of screen (16 sq in) at minimum. Then the maximum, which is what I use, is one on each side of each 2x2 section (4 sq in).

The low guideline has generally been deemed to be too low.

http://algaescrubber.net/forums/showthread.php?1711-DIY-LED-Scrubber-Lighting-Guidelines-and-Builds go to post #101

So the revised suggestion is to have a minimum of one red on each side of every 8 sq in section, that's 2x the light of the original minimum quantity.