Swimming pools blog

Hi
I have a below ground pool with a plastic liner. Is the plastic liner
entirely responsible for waterproofing the pool? Or does the concrete
underneath also keep the water in.
We had a leak recently and found that the water stopped going down when it
was just beneath the light in the deep end. So I took the plastic ring off
from around the light and sure enough the gasket has a half inch gap in it.
Have repaired this with liberal amounts of silicon so hopefully this will
hold.
What worries me is that this gasket is the seal between the liner and the
exterior of the light - I didn’t know whether to also remove the light
holder and make sure there was a seal between that and the concrete wall of
the pool??
Thanks in advance
Nick.