Hi
I picked up a overtank luminaire for a 15g tank (impulse purchase and super cheap)- it's a chinese replica 'based' on an arcadia model in looks. It comes with 3 14w tubes which are white (but seem to be heavy on the warmer side).
It brilliantly illuminates the 15g tank (planning on FO - plans to go Reef long term on my other tank) ) and I knew I may be restricted with replacements but I definitely need to change one of the bulbs to actinic / or closer to the colder side. As this is an all in one unit with no external starter, do you think I'm restricted to the same wattage? I'm guessing that they are 22 inches long (not sure to measure including the pins or not

). I think I read somewhere that similar lights were controlled by a switchboard housed in the unit and I'm gonna be pretty restricted if I have to use identical wattage (as I haven't found any yet). Any ideas?
(I know the old saying 'you get what you pay for' and that T5 lighting and the word cheap should'nt really match but overall Im impressed with the performance for a small tank - just need it to be a little colder).
I guess short of it is - can I change the wattage in a lighting system, or does it have to be specific to the bulb wattage it was supplied with.
Thanks.