I agree with the 6500-6700k review. That is the best spectrum . I was running 5000k & had nothing but problems + I did not like the way the tank looked!. Since switching to 6500k T-8 2x ( 15 watts each) for my 10 , the tank is doing much better & I have zero algae in my tank. I do not have experience with the cfl , but I prefer the T-8 on small tanks like 10' & 20's.