I'm actually starting a project to do the same thing this weekend. I have 3 Hydra 26 non HD over my 90 g. Missing t5 spread and the color, so I'm adding 2 x 36" t5 bulbs to a fixture I'm making. I can't go with 48" or more than 2 due to the rim on my tank sadly, but 2 x 36" should achieve what I'm wanting since I don't really need more par. Going to use aluminum stock for a frame, hold the Hydras in a central channel, and run a t5 on either side of the channel. I'm picking up the aluminum, a ballast, and reflectors from a friend who had extra from changing his light rack and had some older stuff hanging around he wasn't using. I got 6 waterproof LET sockets and standoffs from a LFS in town for $5.00 that they got from a teardown. But pricing all the parts out online or locally I figure I could have done the whole thing with new parts for about $$80 if I had to. I'll try to snag some pictures to share as I put it all together.