It took a while to get our water balanced for which I can only credit the amazing support of TFP experts and members and some sleepless nights on our part. We have enjoyed sparkling water with all the chemistry in balance since the end of June. I now have two questions:
1) The pH is slowly rising (now at 7.8 or maybe a bit more) while the alkalinity is on the low side. From what I read, I should adjust to a pH of 7.5, but this will bring the alkalinity down even further. How do I go about decreasing pH without affecting alkalinity too much? I know that you can aerate to bring pH up again after using muriatic acid, but I haven't read how you can increase alkalinity and not pH. Part of me is hesitant to start adjusting the chemicals because it was so hard to get the water balanced in the first place.
2) We use liquid chlorine (12.5%) and add about 1.5 - 2 quarts a night to bring the FC up to 8. Because we have full sun for 12 hours a day, the FC goes down to about 5 - 5.5 by the next evening. Our CYA is approximately 40 which, according to the CYA/chlorine chart, means we're targeting a FC of 5 and a minimum of 3. Are we overshooting and wasting chlorine? Should we only bring the FC up to 7 at night? Again, after our many prior problems, I've been afraid of hitting the minimum FC on a sunny day or just not trusting that our CYA readings are accurate as this test is subjective.
We use the TF-100 kit and our readings today are:
pH = 7.8 or a little higher
Alkalinity = 80
FC = 7.5
CYA = 38 - 40
Calcium Hardness = 425
Thanks for any advice.