doesnt too much light cause algae? i've been lucky, so havent eexperienced this. i'm sure i've read somewhere on here about a 5 hours on, 5hours off rota or something like that, as the 5 hours on isnt enough to promote algae growth. i'm sure someone can fill in the gaps in my knowledge with the exact timings and help you. basically, less light = less algae! also, can you fit an algae eater in the tank? they'd have a feast! either way, try not to go down the quick fix chemical route as once you start, you'll never get out of it!

good luck and keep us posted.