Overflow advice

[banditpowdercoat]

Silicone doesn't stick to ABS very well. But if you scuff the mating surface with sandpaper, it will increase the "tooth" and the silicones grip. I am asuming he wants a nice round looking overflow in the middle of his tank? It is easy to build a box on the back wall out of glass too though. Silicone really sticks to glass well. Any glass shop will cut the pieces needed and they won't cost much at all.