thanks guys. heard from the acrylic people again today, it takes 7-10 days to manufacture and they will deliver which saves me a lot of messing about. think i will order this friday or possibly tuesday next week after the bank holiday. cant wait to get it ordered and on its way. Next job on the tank is to fit a solid oak frame around the viewing window, glue and screw, to give the front panel a bit more surface area contact and a larger area for the silicone to go, oak is approx. just over an inch thick which should help quite a bit.