I routinely deal with cyanuric acid levels above 200 ppm (I recently tested water for a potential customer that had 700 ppm cyanuric acid. They refused to do anything about it. I declined the account). I try to keep the free chlorine level at 11.5% of cyanuric acid.Originally Posted by chem geek
So, at 300 ppm cyanuric acid, and 35 ppm free chlorine, will the pH test be inaccurate? It seems that it should be fine if the test sample is tested quickly.