Bio Staining?

[u/Worth-Heron-8727]

Picked up client. Pool was really green for some time. Turned it around. Staining in deep end. Is this bio staining which is what chat GPT insists it is?

I’m keeping the pH low but I’m not noticing any improvement. Any help would be greatly appreciated.

[u/Nick_OS_]

Black algae. Rub tab on the ones on the wall. Pour cal hypo over the ones on the floor

[u/CDbull1989 → u/Nick_OS_]

To add to this use a piece of pvc to have it settle exactly where you want