I'd like to know the cause of these stains. I am not set on resolving them, if it's even possible, but I'd like to know what caused them so that we can prevent this from happening after we have the pool resurfaced (next year it's looking like now). These were here when we bought the house, and now that the water is clear they really show up and make the pool look bad.
NOTE: there is NO ALGAE in my pool, the chemicals are good, etc.
My guess is this is etching from a major algae problem. As you can see, the appearance of the stain (they may be 2 different problems) is different up the side of the wall compared to lower down the wall. These stains also appear on the floor in places. It is slightly rough and does not sweep off.
This really isn't a stain, it's a spot on the pool that looks like a repair. It is crumbly, and is NOT a repair. A friend that knows a lot about pools said it is calcium seep from the previous owner not keeping CH high enough. There are maybe 5 of these around the pool.
This spot is on the floor of the pool. It is raised and looks like iron staining. Sorry the picture isn't better, it is hard to get a picture of this spot. So in this case it is sort of similar to Stain 2 in that it's raised from the surface, but the rust color has me more concerned about this one than Stain 2.
Again, I'm not real concerned about fixing these unless it's easy to do, because we plan on resurfacing the pool either after this year's swim season or next year before swim season begins. I am mostly curious, but would fix them if it's not hard.