I know that someone at one time posted a photo of a trichlor puck attached somehow to a stick or PVC pipe or something. It was used to hold a trichlor puck steady to use it like a giant eraser.
I've searched but cannot find it. I think we will need that to get after that black algae in my friends pool. And to have on hand for her family to use on occasion if they notice the spots later, or if we cannot lick that problem in the short time available.
PS, maybe that ought to be put into the sticky "things I thought everyone Knew" or "photo dictionary of pool things"