mr_X
Aquarium Advice Addict
You will definitely need 3 over a 6' tank. Logan from reef breeders will send out a couple blue diodes with the fixtures if you wanted to change out the reds. Otherwise, I bought all of mine on ebay, besides the single reef breeders unit, and all you need to do is make sure they have a lot of positive feedback.
If your tank is 20" deep, you definitely do not need optics. You'll end up burning up more stuff than not IMO.
If your tank is 20" deep, you definitely do not need optics. You'll end up burning up more stuff than not IMO.