I am in the process of doing a SLAM on my pool (CYA 60, FC 30), because my pool had a green tint. A day after the SLAM, the pool passed the overnight test, but I had these little black web like patterns in the plaster.
Is this black algae?
Please see attached picture. The growth is the size of a nickel. We only have ~40 of these little webs in the shallow and deep end.
The pool is now crystal clear, but the little webs still remain.
Also, we had the pool re-plasted last year. Any recommendations?