My Pool Algae Won't Scrub Off

Change Chemicals

• If scrubbing away pool algae isn't working, it's possible that the chemicals and algaecides that you are adding to the pool aren't doing their job; if they are functioning properly, algae isn't likely to still be clinging to the walls of the pool. Algaecides known as quats are commonly found in pool stores, and they are generally one of the cheaper forms of algaecides. They may not do the job, however, and are better to use as a preventative measure rather than to correct a problem that already exists. Polyquats have a similar chemical makeup to quats, but they are considerably stronger and are designed specifically for several types of algae and to attack algae that has attached itself to surfaces. If scrubbing alone isn't helping, using polyquats might work.

Clean Filters

• Once the algae has been scrubbed off the sides of the pool and released back into the water, it is the job of the filter to remove it from the system. If the filter is dirty, it won't be catching all the microscopic algae organisms, and whatever is scrubbed free from the pool will reappear quickly--sometimes even overnight. Be sure that the pool filters are clean; in some systems, there is also sand that the water is filtered through. It may be necessary to change this as well to get the algae off the inside of the pool.

Adjust the pH

• The pH is a measure of how alkaline or acidic the water in the pool is, and this can have a major impact on the success of scrubbing algae. If the pH is too low, the chemicals that are added to the pool will disappear quickly, usually before they can do their job. If it's too high, this can add to the problem of discoloration of the pool walls, and it will make the chemicals less effective. When trying to get rid of algae, the buildup of scale from high pH and the ineffectiveness of chemicals can also make scrubbing algae from the pool next to impossible. The ideal range of pH is between 7.4 and 7.6; to raise pH, add soda ash. To lower pH, add muriatic acid or sodium bisulfate.

Drain the Pool

• Some pools that have a concrete surface may be so pitted and worn that the only way to remove all the algae from the cracks and crevices is to completely drain and dry the pool. Algae thrives in water, so draining the pool and letting it dry in the sun can succeed in removing algae that scrubbing alone leaves behind. In some cases, using a power washer or acid washing the inside of the pool can also help ensure that there will be no more troublesome algae left behind when the pool is refilled.