wierd pinkish stain from waterline up to pool deck

Hi experienced pool owners! Please help an inexperienced pool owner if you can.
This is our second year of opening the vynil lined 30,000 gallon inground pool that came with our house. The first time we closed the pool the former owners came and showed us how to do it. The next spring when we opened-no problems. Water was crystal clear.
This past fall we closed on our own, using their instructions. When we opened last week the water was as green as could be. We shocked and used algaecide , and have been running the filter as well as brushing and vaccuuming. the algae is gone ,but the water is cloudy.
The big mystery though is a weird pinkish stain that runs from the waterline up to the edge of the concrete at the edge of the pool. There is no slime or substance clinging to the surface. I went to the pool store and bought the cleaner that they suggested-Natural Chemistry Clean & Perfect. All it succeeded in doing was taking off a little of the color from the printed on design of the liner.
If anyone has any advice I sure could use it. Sorry this is so long, but I never know what could be helpful in solving my pool mysteries! Thank you in advance.
Maryetta

Post water testing result numbers (FC, TC, Ph, Alk, Calcium hardness, cya) and tell us exactly what all you have put in the pool - ingredients. Then somebody here can take a look at should be able to help.