This is the 3rd season since we've had our inground pool installed.
We have an SWG but once or twice a year have had cloudy water without any combined chlorine and chlorine has always held overnight first time, so I'm not even certain I had algae. Each time I've treated as algae with the shock as prescribed on this forum.
Additionally once or twice a year, I've noticed water behind the liner. Our pool is about 8ft deep in the deep end and the water behind the liner forms in the deep end just above where the sloped side wall rounds out to the flat bottom of the pool. (I don't understand why the water doesn't simply flow down to the pool floor) The affected area is about 18" high and up to 6'-8'long. When I push on the liner it feels like about 1/2" -1"deep and usually goes away within a week.
Each of the three years we've had the pool in early August, both cloudy water and water behind the liner occurred simultaneously and correspondingly disappear around the same time. The first year we had an incredible rain storm where the water went as high as the coping, so I thought the water could have went over top of liner, but that's not the case for the 2nd and 3rd year. We live on top of a hill, and I've never heard of any drainage / water table issues.
I usually notice the water behind the liner I vacuum after an algae shock. The vacuum stalls over the spot in the pool as the liner gets sucked closer to the vacuum opening, and the pressure on the filter drops.
Should I be concerned about occasional water behind the liner?
I'm wondering if there is a relationship between cloudy water, and water behind the liner?
Is it possible that one causes the other, or they have both have the same common cause.