Go to Grimreapers big thread on RC with PAR ratings of bulbs and how much the better individual reflectors(like on the Aquactinics Constellation) versus a single parabolic reflectors.Sense less light is wasted from the back of the bulbs it does nearly doubles over having no reflectors and even a single reflector.
Melon,I know that added price of buying the bulbs is expensive but I believe you will be happy in the long run.The slimpaq bulbs on the Nova Pro really are low in PAR and the color they give is pretty bland.You can get outstanding color by choosing your own,choice is everything.I was amazed at the color difference between my old Nova's against the Aquactinics with my bulb choices.The price was more like $250 for bulbs.I paid $280 shipped from Reef Geek for 16 bulbs,two additional 6500k for a different look.24'' is getting pretty deep,if going with T5,consider the Aquactinics because it has better reflectors and bulbs like the ATI has 30-40% better PAR than the slimpaqs.The fans are on the top and blow upwards,much quieter than the Nova's but I can still hear them somewhat.