Are you just redoing the large seams or the structural inner seams?

If it's all the seams, I'd use a stronger product - GE RTV108 is what was recommended to me. You probably won't find it at HD or a local hardware store, but Acklands-Grainger should have it (there are 5 locations in Calgary).

Thanks for the info everyone.

I am only re attaching a black insert that is fixed to the back wall inside the tank (and creating a seal between it and the overflow) so I think regular silicone should be fine.

Palmer

I used Rona brand it's aquarium safe and only 5 bucks a tube