Re: 4ft T5 with 4 bulbs.
I have this fixture for my standard 75 gal.
*4- 6500 K bulbs come with it
*No active cooling system (runs quite hot)
*Casing is just smaller than the rim of the aquarium- can make mounting an issue- unless you plan on suspending it from the ceiling.
*Has an additional outlet on the case itself if you wanted to daisy-chain a cooling fan or other fixture.
*2 separate switches so you can run only 2 bulbs if you want
Hard to argue with the price if you can mount and cool it yourself!