I built a small pond in my 18x18 viv for my whites tree frogs. I used GS which didn't cure and left a horrible mess. I was able to clean most of it up but some of it turned into an extremely hard plastic like substance which I just left in the bottom and foamed over. I then applied 5 coats of drylok and performed a leak test. Sure enough the pond leaked from at least three spots so I decided to silicone up to the water level. After applying a large amount of silicone and letting it cure it was on to another leak test. Sure enough more leaks. Now several days later and an entire can of silicone I will be testing again tonight and if that pond leaks I may just have a mental breakdown.