Thanks all.
Thomas, with the amount of food I chuck in there is plenty to go around. With 10 geos, 9 plecs, a pictus and 6 hungry uaru that have no objection to eating off the substrate I can chuck in massive quantities of food and not have to worry about it going uneaten and spoiling the water. There are three 2kg buckets under the tank, one is crumble and one is flake!
Fishybuisness, the tank is 2400mm long, 977 wide and 620 high. It was fairly cheap because Greg had a piece of tinted 12mm glass that was the perfect size for the base, thus the strange dimensions. I had asked for 900 wide originally but then asked how wide the glass he had was and decided it wasn't worth trimming 77mm off it.
Al, after getting a good close up look at the barbs on the rays in Richards tank in the UK, and at how rough and textured they are, I decided against the underpants method.
P44, I think the uaru would accept that challenge....