Thanks for all the help everyone, I'm going to make the coast to coast on the inside like banditpowdercoat, because although it would be less obtrusive on the outside, to do that I would have to take a long thin section out of the back panel which is somewhat outside my comfort zone at the moment!

I notice that the Herbie style drain seems to be popular, I think I'll do something like that with a third emergency emergency drain because I'm paranoid (and the turbo snails seem to take delight in ending up in the weirdest/most impossible places). I figure that if I use 1.5" tube instead of 1" I should be able to cope with pretty much anything that's likely to happen. I hope! :biggrin:

I guess now I've got what I'm building sorted I'll have to do some head scratching and work out exactly how to build it..

Still not looking forward to drilling holes in the glass though! :neutral:

Drilling tanks is easy. Just need a cordless drill, or one with good speed regulation, and a diamond hole saw. Start SLOW speed, using your hand to hold the bit steady, but at a slight angle untill it starts its groove. Then slowly tilt the drill perpenbdicular. Dont push on the drill, let the weight of it do the work. Ohh, water fro bit cooling too.

There are some great how to vids on youtube on drilling glass.

a glass shop would take a 1/2" off that for about 20 bucks.. I also recomend a external overflow but if you don't have the extra 4" behind your tank then you can't.

as for 1" pipe.. it is to small for what you want using a durso. I would go two 1.5" with a durso and a durso is still loud. people have been having luck with the herbie set up using 3, 1" pipes. a herbie will handle more flow for the same size pipe as it is a syphon set up not a gravity feed setup.

Steve

After reading the article on wetwebmedia I've decided that 1.5" is the way to go - I am going for the Herbie, plus an extra emergency drain. I figure that should handle the 800(ish) GPH that I'm planning on even if there's a blockage in one pipe. I'm away form home most of the day, so I want it to be as disaster proof as possible!

I could arrange the extra 4" behind the tank, as I'm building my own cabinet to go underneath it. I'd have to accommodate the plumbing behind if the bulkheads were in the back of the tank, so if I put them in the bottom of an external overflow I should be no worse off for space that way.. The problem that I can see is that there's a trim around the top of the tank that I'd have to cut back a bit because I want to have the water level above the bottom of the trim at the front and sides so it's not visible. I'm not sure if the trim is structural or not. Having said that the overflow would act as a brace wouldn't it? Maybe if I can get away with shaving say 1/2" off the trim and whatever else off the glass.. ?

Rob.