I'm looking at getting the 46" uvl t5 bulbs but I don't know what combination of them? My fixture has 6 bulbs and they can't be longer than 46". Its a catalina aquatics fixture.
48" bulbs are not actually 48" long. Any of the major brand 54w 48" bulbs (ATI, Geisemann, UVL) will be fine.
Maybe:
ATI Blue Plus
UVL Actinic White
ATI Blue Plus
KZ Figi Purple or UVL Aquasun
ATI Blue Plus
ATI Aquablue Special