I have a plaster pool. Never have had any issues with algae. I was brushing the pool floor tonight and noticed this spot that would refuse to brush off. I even flipped the pool brush over and pushed the hard side against the spot and nothing.
Is this black algae? I zoomed in very close. The spot looks to be about the size of a half dollar.
Is this black algae? I zoomed in very close. The spot looks to be about the size of a half dollar.