We have an inground pool with a vinyl liner. This year we noticed our deep end looked very yellow on the bottom, and the discoloration is now visible along the edges on the pool, and in some cases on the walls. We have spent quite a bit of money at the pool store, having the water tested and trying a variety of chemicals. Yesterday they insisted we add a 60% algaecide but this has made no difference. The water is clear and the edges do not feel any different. Brushing it has no effect. (In researching this problem I thought it might be scaling, but there is nothing to sample- just this discoloration. We were told it was mustard algae but from what I've read, it doesn't seem to match the descriptions.)

My husband is off to the pool store, but I don't think they really know what is going on and just selling us a variety of things to try. If anyone has any suggestions, I would sincerely appreciate them. Thanks!