
Originally Posted by
chem geek
The CYA level may be more than 100 since that is the limit of the test (the black dot could disappear before one adds enough "cloudy" mixture to the tube to even get to the 100 ppm line).
Unfortunately, the only real way to lower the CYA is through dilution which means partial drain and refill. However, since this is near the end of the pool season and winter closing is approaching, the pool can just be made to have higher than usual chlorine levels until winter closing. Then the CYA may drop over the winter (for reasons that are not fully understood yet). If the pool is in an area where there are winter rains, then these can be used for dilution via overflow (but if it's in a freezing area, then that may not work as one usually lowers the water level below the skimmer and inlet returns).
Richard
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