fidojoe IMO you could go with just 1 of those Clamp on MH light if you want to, I have only one MH on my tank and it's 30x30 but I do use 130w of PC actinics. Did you get the fixture from hellolights.com ?
Let us know how you like the Coralife fixture I'm thinking of starting up my 42 hex again and that light looks like it'll work great
