Problem Solver - August 2011
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Prevent Pool Shutdowns

In the midst of a heat wave, there's nothing better than diving into the pool. People of all ages love to swim during all seasons, but aquatic facility managers must be diligent to protect swimmers form illness. Cryptosporidium, a tenacious recreational water illness, causes severe gastrointestinal illness and is resistant to chlorine.

It is critically important to use the right amount of chlorine, and other water treatment solutions, if you want to protect swimmers from this and other RWIs. For example, cyanuric acid increases the amount of time it takes for chlorine to kill harmful microorganisms. And as the level of cyanuric acid goes up, the activity of free chlorine is slowed. Being aware of the correct levels and procedures for treating pool water is essential.

Q: What is cyanuric acid?

A: Cyanuric acid is a weak acid used to stabilize chlorine in swimming pools. Free chlorine in pool water breaks down when exposed to the sun's ultraviolet rays. Cyanuric acid aims to reduce this loss of chlorine. But cyanuric acid can interfere with chlorine's ability to kill germs in the water.

What's more, it can impact your pool's ability to stay open. One study showed that more than one-quarter (28 percent) of commercial pools with moderate to high stabilizer (21 to 100 ppm) were shut down due to water quality issues between 2007 and 2009. This compares with just 13 percent of pools with levels at 1 to 20 ppm.

Q: What is the proper level of cyanuric acid?

A: Many recreational water facility operators are not aware of the proper levels of cyanuric acid for their pools. You should limit the levels in outdoor pools to 20 ppm. Indoor pools and spas should not use cyanuric acid at all.

Q: What else should we know?

A: In addition to limiting your use of cyanuric acid in outdoor pools, you should take several other steps. Check the levels on a regular basis, at least once a month. Keep a test kit on hand and educate your staff on how to use it and understand the reading. Be sure to find a high sensitivity kit. (Some do not measure levels below 30 ppm.) Also, never add more cyanuric acid to your pool without checking the current level first.

If you find that you need to reduce cyanuric acid in your pool, you'll need to partially drain the pool and then add fresh water.


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