copper algaecide - bad for environment?

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.

copper algaecide - bad for environment?

Postby tom » Mon 09 Jan, 2006 08:20

I have been advised by a chemist, who is an environmentalist, that I should not use a copper algaecide. Our sewer treatment plant supports a wetland, and it is possible that the copper passes through the plant and into the wetland where it may kill vital plants and animals.

Does anyone know where I can get more information about this issue? I would like to judge the truth of this issue by scientific studies and published paper, not just personal opinion, from self appointed "experts".

Any suggestions?

Also, does the EPA approval of a swimming pool chemical mean that the chemical is safe for the environment or just for the use it is meant for (human health)?

Eventually, everyone has to dump their pool water somewhere.


Copper algicides

Postby Algea » Wed 11 Jan, 2006 14:54

The use of copper as an algicide is usually at a level below 0.7ppm. The EPA has set the limit for copper in drinking water at 1.3 ppm. See copper in drinking water. If the issue is low level copper residue from a 20,000gal pool being emptied into a wetland catchment area of perhaps millions of gallons, then the effects of this copper will be almost non-existent.

At least copper is a natural mineral that is found freely in nature, as opposed to the polymeric algaecides and lab-produced clarifiers which are sold commercially for swimming pool maintenance. These would probably have more of an effect on the wetland ecosystem than the low level copper used in pools.

More information on the EPA's copper standards and specifications can be found at Aquatic Life Copper Criteria.

According to this freshwater species guide, daphnia pulicaria is the most sensitive at 2.54 mcg/l. In pool water a level of 0.7ppm equates to 0.7mg/l or 700mcg/l. So I guess dapnia would not live in the pool, but then the question is whether the discharged water will mix with at least 275 gallons of source water to ensure that the level is lower than the 2.54 mcg/l that would destroy half the daphnia colony (if assumed present).

One should also keep in mind that the copper in the discharged water will be synthesised and broken down on contact with algae, so the level will have a downward trend as it approaches the wetland area. For information on evaluation and testing of copper as a pollutant see this document on discharging copper.

Good luck with the project Tom

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