Algae and Algaecides

The three most common types of algae we will contend with are green, mustard and black algae. If correct balance ranges are maintained and concentrations of TDS, water hardness and Cyanuric Acid are where they should be, if we maintain a constant chlorine reading of 1.0 - 1.5 free and available all the time, and if the pool and filter are cleaned as needed, we should not have algae problems, sounds easy. But there are too many variables in water that either slow down or stop the killing power of chlorine. We must try a procedure that gives more constant chlorine levels. One procedure is using trichloro tablets and offline chlorine feeders, or leaving liquid for customers to add in between calls. We should also consider using some type of algaecide, at least during swimming season.

Green algae
Is the easiest of the three to kill- usually by super chlorinating with liquid chlorine, cleaning the filter, brushing or vacuuming the pool, running the pump longer and employing an algaecide.

Mustard algae
Can grow overnight in clean, clear, sparkling water. A film of alkaline or some other mineral tends to form a coating. We should steel brush this off before treatment. I have tried most types of algaecides plus chlorine enhancers to activate the chlorine, and have better luck with the old standby, copper algaecide. I use 7% copper, adding one pint to an empty gallon jug, add 7 pints of water and add one pint diluted solution to the pool every two or three weeks during the summer months. This solution should not add to much copper; if pH and TA are not allowed to drop to low and I do not over chlorinate, I do not have the copper drop out (come out of the solution into a solid and cause stains, plug the filter or cause swimmers’ hair or bathing suits turn green). Above 0.2 ppm copper, a chelating agent or metal inhibitor may occasionally be needed to hold copper in solution until some water can be changed to reduce the copper concentration.

Using copper, I find I use less chlorine and maintain a lower chlorine level (around 1.0 ppm). If I use some of the quatanarry ammonia-based algaecides, they tend to dissipate in sunlight and high chlorine levels or become trapped by the filter. I consider these more of a short-term algaecide. The copper will stay unless it drops out. It works along with the chlorine much longer, but copper can be bad news if there is too much, if chemical balances are off, or if chlorine levels are high. So, if you intend to use copper, consider all the good and not so good factors, or use less copper in conjunction with another type of algaecide if they are compatible. The black algaecide that have both copper and some type of ammonia should be considered. I stick with what works for me, but it may not do the same for the waters in your area.

Can be bad news, as it tends to thrive in cracks and porous area in plaster. It forms an oily, protective film over the roots, and even the best algaecides or chlorines available will need some help. Steel brush off the tops, then treat with additional chlorine or an algaecide. Be sure the pool and filter are clean. Algae thrives on sunlight, dirt and other contaminants. So if we can keep a constant chlorine level, occasionally add an algaecide, keep the pool clean and leave chlorine to be added between calls, we should be able to whip any type of algae problems that we find. I stress to customers that if they have black algae problems they should add the chlorine I leave and consider buying an automatic pool cleaners. If the pool has or has had advanced stages of black algae, I will not service it, as on call per week is usually not enough to control black algae. I recommend sand blasting and then chemically treating the pool, either replastering it or painting with epoxy pool paint. I have seen black algae grow through chlorinated, rubber-based pool paints. Another alternative could be fiberglass coating.

If you catch algae in the early stages, treat it correctly and maintain proper balance ranges. Keep the pool and filter clean. Be sure filter is in good condition and is adequate to filter the amount of water in the pool. Consider installing an erosion-type automatic chlorine feeder. Change some or all of the water as needed to reduce mineral build ups. Be kind to your mother, lead a good life, give it your best shot and you should be able to whip that algae problem. Remember, when using copper- based algaecides, do not overdo it. If in doubt, test the copper concentration occasionally. If it is above 0.2 ppm, use metal inhibitors until you change some or all of the water. See the section on Super chlorination for more information on when and how much if combined chlorine is above 0.3 ppm.