New member, been reading through old black algae threads. My pool is in Florida and receives moderate sunlight throughout the day and is never covered. Last year I had black algae start in the more shady areas of the pool. I've noticed there are more spots where the plaster finish is more worn. Refinishing the plaster and draining the pool are out of the question. Refinishing costs too much and draining a pool in florida usually means it will pop up due to the low water table. Last year I went through a regiment of Leslies black algae killer, but it literally did nothing. I even got in the pool with a scuba tank and wire brush, hitting every area I could find. I found if I leave a trichlor tab on the spots over night it will disappear, but even the ones I killed last year are back. This year as summer comes ive decided Im going to defeat it, but now its spread more and there are probly hundreds of spots, beyond hitting them with a tab. I dont know why, but I bought another half gallon of black algae killer after being told once I add enough they should brush off..........I'm a sucker, but after brushing my pool for the fourth time today and having no effect on the spots I feel like Im going to get no results. I need some more options.