How many Cree LEDs do I need (20 gallon)

This is an SPS tank that currently has 250 watts over it. How many Cree LEDs would be good to replace this halide setup?

I'm looking at Rapid LED right now. I want a full spectrum unit, so I am thinking that I should include Royal blue, NW, violet, deep amber, cyan and green LEDs.

Tank is 24" x 12"

 

Rapid recommends 34 for a 40 breeder. If I take half, that's 16.

 

Which is probably about right.

I'd lump all 4 of the "other" colors in the center.

 

Dead center?

Do you think I would get away with one driver if I never drive the diodes at 100%.

 

Enough white?

 

I think I will have a 3rd row tapped, but I will leave the diodes off of it. I will expand to a 55 gallon in time, as I have already built the stand and canopy, but that won't be for at least a year, probably more.

3 rows of 8 would give me 48 diodes, which would work great for a 55.

 

Product How To's
Full spectrum LED layouts - Lighting Forum - Nano-Reef.com Forums
HTH led groupbuy is a good source for crees, steves is better for luxeons.

 

Those link confused me. There were lots of links within the first.

 

Yeah, many of them are helpful.

 

NM, I figured it out. Those clusters really bring the price up a bit. For power, I need a power supply and two meanwell drivers?