Lighting anmd diy fixtures

[omarh]

so i'm in the process of working out a DIY 6 bulbs fixture for a 90 gal.

i already have a WH7 ballast on hand bu i need to buy another one (either a WH5 or WH7)/ i was thinknig of getting a WH7 so that i can turn on 3 actinics and 3 day lights but i can also have 2 actinics on WH5  and turn those on in the morning followed by 3 daylight and 1 actinic on the WH7 an hour later.
is there a difference with these two lighting options or is it purely asthetics?