Vacancy under leak

[CanuckPool]

I know there is caulking you can use to seal your rain gutters when they are leaking, and you can use it underwater, maybe you can try that.

[AndyT86]

A friend who used the same PB reminded me that the Pool-Lite was dumped out in dry powder form, then they sprayed water over it to "damp set" it. So apparently it was not a concrete pour.

I'll check into that gutter caulk. I know it can be applied wet, but do you think it will cure without exposure to air?