I'd like to build a T5HO fixture, but more than 24W of T5HO is going to be too much for my tank. I can't find a ballast that isn't 2x24W though. Short of buying the Hagen Glo Linear Flourescent T5HO strip I don't really know what to do. I'm assuming you can't just use 1 of the 2 "parts" of the 2x24W ballast.
