Getting rid of Diatoms

[Michael]

(probably a common question...but forget the answer) ops:
My tank is getting covered in brown algae. I think a piece of liverock also has aptasia on it. I've read about this before, but forget the solution...aside from reducing the time the light is on, and the amount of food being fed, is there anything else to do?
I thought one type of shrimp ate aptasia...forget which one though.
--even though this 72gallon tank is fowlr...do I need reef crustaceans? Currently I have a damsel and a cleaner shrimp in the tank.

Thanks

Michael.