Lighting: T5 vs Metal Halide???

[moppy]

Already have to use AC in the room (which is not cheap to run as I'm sure a lot of you know)

Right now I have 150W MH on my 90 corner tank and I'm not sure it is enough.

I want to move the 150 W to my 40 breeder and get a 250W for my 90 corner. Hoping that that will be enough but I've just heard a lot of talk about T5 and wasn't sure whether to upgrade to 250W or a combination of T5. I don't have sps right now but would like to try...