[mordoria]

CFLs will get very warm. The price is good but, if you cant keep your temps down, dead frogs are more expensive. try and raise the light off the top and have a fan that blows on the lightbulb.

I bought a 24" T5 HO Aquarium Light Hood Freshwater Plant Tropical Fish 6500K 48W Odyssea | eBay
It seems to work great on my 20H.

 

[mordoria]

I like to have 2.5 watts per gallon.

 

[mordoria]

If you dont have frogs, then heats not such an issue. I have an empty viv thats for plants, it loved having 2x23w cfls. I raised it up off the tank for some air flow and to help spread the light.

As for the 24", I like it on my 20H. I love a lush tank.