Is there a magic set of number by which we can keep our eyes open under water without risk of irritation? I have seen the recommended chemistry levels and the CYA chart. I also read tears have a pH of 6.5-7.6 with average of 7.0. My plaster pool is running pH:7.5 but since my CYA is mid-range at 50 ,I have to keep my FC at 6. Would it be worth my time and expense to lower the CYA so I can have a lower FC level to potentially reduce eye irritation?