I have tried so many bulb combos in my 4 bulb t5 and the one I like best is. 2 kz super blues(much nicer thant ATI blue plus, kz Fiji Purple(again much nicer than ATI purple plus) and a Geiseman pure Actinic. The KZ bulbs are much brighter than ATI and have more par. Better colour as well. Aquablue specials or anything in that coulour range wash out colours. This combo gives you a nice deep bright blue. Run one super blue with the Actinic for night time and then the fiji purple and the other super blue for daytime. Since replacing the 2 ATI blue plus with the KZ super blues the response from my corals have been great.