Been fighting this crap for a while. I think I am going to drain my pool down below the areas where it is growing (sides, steps, beach area). What should I hit it with after I drain it? Power wash it? Scrub with chlorine tab? Anyone ever fight this stuff? Thanks.

Second troublefreepool SLAM for this. Had similar results as JDCAG.

Check your cya levels
You may not be getting your chlorine levels high enough to completely get rid of the problem.
For example my cya is 110-120 ish so I'd need to get the chlorine levels to 55ish to completely get rid of the algae. Because of this I'm going to drain my pool to get levels back to the 40-50 range so I can keep my chlorine at a more manageable level.

I agree with the SLAM method mentioned above and making sure to check CYA levels. The only thing I have to add is that (if I recall correctly) black algae needs to be brushed throughout the process to remove the protective coating on the algae. In my experience, it could take several days of holdibg the chlorine at shock levels.

Good luck.

That's what I have read too about the black algae. I read it has the protective layers and it has roots that grow in to the plaster. You have to brush it daily while at shock levels. I will try all your suggestions first and go on a vigorous brushing schedule. Thanks for all the suggestions and any others you might have. This stuff is a PITA!!!!

Good luck! I SLAM'd mine for weeks, brushing several times a day and even rigging up a pumice stone to scrub with. I never could get rid of the stuff completely. I got it down to where half of my pool looked like it had tiny black freckles. I am just keeping those at bay until I plop down the cash to have it resurfaced, which has been in the plans for a bit anyway.

Yes. Ran into this at a city pool I used to work at, and daily wire brushing was the only way to eliminate it.

Do a SLAM on your pool. You need to check the CYA level and adjust your chlorine accordingly to do a proper SLAM. I fought black algae over the summer and a SLAM took care of it along with some other methods. I scrubbed each individual black algae spot, because they develop a film over the top of them to protect it from chlorine. You need to break that film to get exposure to the chlorine. For those hard areas, I took a chlorine puck and actually rubbed it directly over each spot that was tough to get. That was after you break that film over it of course. This should take care of it. Oh, and make sure people who come swim have on a clean suit, especially if they have been to the beach lately. That is how you can get black algae. Good luck. Feel free to PM me if you have any questions.