How do you treat black or brown algae in a plaster swimming pool?

Answer 1

Black Algae is the toughest of all to get rid of The best thing to do wit it is scrub it so that the waxy surface of it is thoughtfully damaged then shock the pool and hit it with a strong algaecide. A pool shop will be able to recommend the right product to do this.

Answer 2

With a stainless steel wire brush. Brush the spots fairly vigorously and then add a liquid algaecide especially for black algae. Follow label inst. You possibly could also try a little bit of granular chlorine directly on each spot letting it sit with the circulation off. To get the granular to the spot - use your pool pole with the insert part of the handle removed and use the tube part as a funnel holding directly over the spot. Be careful here as this method may bleach that area of the pool but that would be better than having blk alg. Hmm, you shouldn't be getting blk alg. in a fiberglass pool. Someone is not watching chlorine levels and cleaning the filter as needed. You may also want to try rubbing a chlorine tablet on the spot after brushing it.

Ken

I use ultrasonic algae control www.lgsonic.com it takes about 3 weeks but the product works fine for me.

Answer

Suspicious that you fibreglass pool has blackspot? I would say you have a black stain caused by too much copper in the water or a type of osmosis caused by a concentration of cobalt in the gel coat. Is the "black algae" slimey and sitting well above the surface of the fibreglass? Black Algae needs an anchor point where it's root can attach and fibreglass does not give that unless your pool has a crack or something similiar.

Answer 3

You are limited to using liquid black algae treatments.

k