Miles,
I assume you're here in the UK ??
I found ND Aquatics
AC Aquatics
Poseidons Palace
I went with AC, If on schedule it will be here the start of april, until then i can't say anything good or bad lol
Went with 6x2x2 (largest size for the space i have)
I went with glass as they're all i'm used to really, read obviously scratches can be made fairly easy in other materials, did also read about opti-white so went with standard pilkington (really am in two minds whether i can ammend my order to front/sides in opti)
Also the bracing put me off using anything but glass too, i read they use many more bracings which would hinder what i wanted to do
Then again, as long as you respect whatever material is used i can't see problems
TTFN
Tony