refugiums
 

what is the best light to use 10k, 5500k, 6500k etc.
also what do you reconmend for the best macroalgae?

5500K is probably pretty good, but anything between 3000K and 6500K should work well, for growing macro-algae's anyways.

Cheatomorpha tends to be considered the best macro because it is non-sexual and tends to grow fairly well and in a controllable fasion.

Hope this helps, Cheers,

Chris