High phosphate is not a problem, that said, you don't need too much either.
They are raised 8 inches, on for 8 hours per day. I can turn one bank off if I need to, but so far, I have less problem algae with this setup than the original single CFL I had. If you guys think I should, I will.What you really don't need is 4 T5HO bulbs lighting a 13 inch high tank. Even one bulb is too much, unless you have it raised about 8-10 inches above the top of the tank (assuming that you have a good quality T5HO light fixture and not a FishNeedIt light). Two widely spaced bulbs would help in covering the whole front to back depth of the tank, but those, too, would need to be raised 8-10 inches to keep the intensity in reasonable limits.