My CH varies a lot. Maybe it is me and my testing. I use the TF-100 and it always is difficult to determine how much of a color change is needed to arrive at the number. So my CH may actually be higher. But, I digress. My CH was up to 550 on July 1 when I left on vacation and is now 470. We had a lot of rain and that must have brought it down.
Here are my current numbers
CYA 95 (Use pucks to keep the FC up during vacation)
I tested my fill water today and got the following:
FC 2, CC 0, TC 2, PH 7.5, TA 280, CH 270, CYA 0
I know I can manage the TA with aeration and with normal back washing and draining (due to rain) the CYA. CH is the question. The Pool Calculator says my goal should be between 50 and 300. Obviously I cannot get below 270 without using rain water, so 270 would have to be my minimum. According to the calculator I need to replace 85% of my water to get to 300. My question is what is a realistic goal for CH for my vinyl ABG pool? At what maximum level should I absolutely start to worry? And finally, how would you go about lowering the CH - all at once or with normal backwash & lowering due to rain or some other method?