I use oxyspa,100% pure DuPont® Monopersulfate Compound (spa activatior) which is a MPS ,I order from Spa Depot on the internet, I believe it is buffered, as my primary sanitizer. My tub uses a Silver Iodine cartridge inside spa filter and Ozone. Once a week I use 3 oz of activator as a shock and sometimes ocassionally substitute Sodium Dichlor instead of the activator as the shock. Water is usually always very clear, but the PH seems to be very low each week I test it. I know I could do a water change, but its freezing cold here and would like to put that off till warmer weather. Just wondering about the low PH?
Thanks