Black spot algae clings to pool surfaces, grout and between pebbles. It is very resistant to treatments and difficult to control. Prevention is much easier than cure.
Firstly prepare the pool water ensuring that the pH level is between 7.2 and 7.4ppm (parts per million).
Black spot algae has a hard crusty shell therefore you must firstly brush the black spots with a stainless steel Pool Pro Algae Brush or for pebble pools a Pool Pro Pebblecrete Algae Brush. This exposes the root growth and assists with the penetration of algaecide.
Add Pool Pro Black Spot Remover as per the instructions on the bottle or from you Pool Pro Professional. This product is copper based which has been found to be the most effective algaecide for black spot algae. Switch on the filter and run for eight hours to circulate. Vacuum the following day and clean filter.
Care should be taken not to overdose with copper based algaecides. In addition, instructions should be carefully adhered to. Over treatment with copper can lead to staining of the pool interior and turn blonde hair green!
When black spot is prolific you would be best advised to have your Pool Pro Professional visit and attend to the problem. In some extreme cases the pool may need to be drained and acid washed.
Never add any alkali material (i.e.: buffer) to the pool when treating with copper based algaecide as this can cause the copper to drop out of suspension and stain the pool interior.