I use two AquaIllumination Hydra FiftyTwo +HD units in my 450gal. They're very nice but the highest % I ever have them set to is 18% for 30 minutes two different times during the day when I like to view the tank. Realized later these are made for salt water reef aquariums. I'm sure I could have purchased something cheaper somewhere that is more appropriate.
Hopefully someone else will chime in with some other suggestions.