Algae Problems in Swimming Pools

Perhaps the most common problem associated with swimming pools is algae problems. This information will help you understand some of the problems involved in dealing with algae in swimming pools.

There are some 24,000 known types of algae and they are all distinguished by being single celled organisms, capable of photosynthesis, mitosis and meiosis. That is, they produce their own food. All cells can divide and reproduce by combining with other algal cells.

In swimming pools the ideal environment can exist where there are periods of zero chlorine. The problem for pool owners is the short life cycle of algae, sometimes as low as twenty minutes. Under normal growth algal blooms can take less than a day to mature into a green pool.

At the first sign of adversity, the algae population goes into a reproduction phase where two cells meet, parley and combine to produce eggs or spores. The size of the spores is less than 0.2 microns. DE filters filter 5 microns and above and sand filters 20 microns and above.

Algae will die from chlorine with concentrations as low as 0.05ppm but spores can resist chlorine levels of up to 10ppm. Salt chlorinators and normal daily chlorine dosing does not achieve those conditions. A manual chlorine dose would need about 1-2 Kg of calcium hypochlorite equivalent to be effective.

Spores, however, cannot tolerate copper salts as copper attaches to the shell or (endospore) preventing germination. Quaternary algaecides are synergistic with copper salts hence the myriad of formulations for control.

Watermaid advise that the first step should be to lower the pH (generally by the addition of up to 2 litres of pool acid) and then followed about 4 hours later with a copper treatment to attain a 1ppm copper level in the pool. 70 grams (about 1 heaped tablespoon) of copper sulphate dissolved in 10 litres of water spread around the pools is the most economical method. But the use of any commercial copper based algaecide will do. Lowering pH is an essential part of reducing plant resistance.

After about 12 hours a stainless steel brush, and a garden hose fitted with a brass jet gurney (available at all hardware shops) can be used to remove stain from the walls. The next step should be to flock the pool (Alum has been used as the traditional method of choice but any pool clarifier will do).

Overnight the debris will settle on the pool floor as a blanket of debris which should then be vacuumed directly to waste and NOT through the filter. After this treatment a pool should attain its clear clean condition within several days of constant filtration and adequate chlorination.

Finally we strongly recommend the use of Lanthanum Carbonate ("Starver") to reduce the phosphorous content to less than 1 part per billion. This starves the organism of an essential element for growth.