I had mild staining to my vinyl liner 4 weeks ago. I rubbed a spot with a lemon and it went away.
I reduced chlorine to almost 0 and did a vitamin C treatment. Worked great. All stains went away. Per instructions I waited 4 days to shock. In that time massive algae bloom occurred. I did 2 green & clean treatments (which entailed raising PH to 8.0 then super chlorinate ) this failed over 1 week period. Also added non copper algaecide... To no avail. Deep green pool.
I shocked the pool with 12 lbs of 73% calcium hypo and 5 lbs of dichlor. This started to work. Started to clear. Now just grey and cloudy. I replaced the cartridge filter with a new one and added clarifier. For the last 5 days pool staying grey and cloudy.
Continue to shock with 99% sodium dichlor w/ 55% active chlorine. 4lbs per day. Still grey and cloudy.
FC goes to 5ppm+ then goes to 0 over night.
4 weeks in with a green/grey pool. I have put another 10 lbs of dichlor in last 24 hrs and FC again dropping. I would appreciate any thoughts on chlorine breaking point or other strategy.