Quote Originally Posted by haze_1956
I went through this same thing over the weekend.

Thought it was algae that kept growing in the same spots

Turns out I have a lot of small divots in the liner, on the bottom of the pool. I am thinking they formed over the winter.

Dirt was collecting in them as the water circulated around. With a little more dirt being added each day, it looked like algae growth

Finally just kept vacuuming this past weekend until I got rid of it.
I get the same thing, especially when no one is in the pool. I've come to realize it is dirt when my yard or the neighbors yard is being mowed or when it is real windy I get a lot of debris that settles in the divots of the liner. As long as they don't "multiply" I can live with it They vacuum or stir right up.