Black algae in pool water can be one of the toughest types of algae to get rid of. This is because unless you kill it at its root, it will sprout new heads and continue to grow. Today we're going to look at how to finally eliminate black algae and make sure it doesn't return.
Unfortunately, black algae can grow even if sanitizer levels are within their best range, because of the protective layer each head has which prevents chemicals from entering its pores. It will appear as black, or blueish/green, and generally more common in plaster or concrete pools.
If you're absolutely sure that you have black algae then here some steps you can take.
This method is for concrete or plaster pools. Do not attempt this treatment with vinyl pools or you will have a lot of damage. Below is another method for vinyl pools.
Fist you're going to need to a very stiff pool brush you can use to brush the affected areas. In addition, you will need chlorine tablets and any general purpose algaecide.
Begin by making sure your pool pump is off and brush the affected areas to get rid of as much by hand as possible.
Next, using the chlorine tablet, spot treat the areas. Once you've sufficiently spot treated each area, pour the all purpose algaecide over them. Let it sit overnight.
The algaecide doesn't actually harm the black algae, it helps take away the barrier found in the heads that prevent chlorine from doing its job. So by using the algaecide your chlorine spot treatment will be more effective.
The next day, brush and vacuum all the dead algae. Repeat if necessary.
For Vinyl Pools:
Vinyl pools are much easier to deal with in regards to black algae.
Brush treat the algae spots every day until it disappears. It may take several days as this type is very resilient, but keep at it and your problem should be solved!