Morning!

I’ve tried just about everything I can think to get rid of this problem. All around the pool liner, on the walls, starting about 2 feet below the surface, I have brown vertical lines that follow the corrugation.

I have a 24 foot round above ground pool. After the latest winter I had a ton of algae in the pool, algaecide, tons of shock, vacuumed to backwash, and switched to a new filter...it's all dead. The water is balanced and crystal clear; I’ve had it checked at the local store several times. The pool floor is perfectly blue. It's just the stupid walls!

I’ve tried brushes, even a kitchen sponge, I’ve spent hours scrubbing and so far nothing is working. It makes the pool walls look dirty and is driving me nuts.

Anyone been through this have maybe have a tip?

Thanks