We had been using a solar cover to keep the water temp around 82 degrees, but fall finally arrived, and we had to give it up. pH had been a stubborn 7.2 - seemed like the solar cover was surpressing the pH. TA was 100.
Took solar cover off 2 days ago, started shocking due to a bottom dwelling algae/pollen problem- I was not keeping FC high enough- I may have been misreading the CYA tube.
Now, pH is 8, with TA only gone to 110.
Changes: No solar cover
Temp of pool dropped 10 degrees in two days
1.5 inches of rain
switched from cal-hypo 65 to bleach for chlorine
air temps dropped 20 degrees
Question 1: On reading the CYA tube- when is the dot "gone". I was adding the test water with CYA reagent to the tube until the dot was completely obscured- not even a hint of a shadow. That gave me a CYA reading of 45. Keeping my FC at 5 based on that reading allowed algae to happen twice- though both times there has been contamination added to the pool around the same time- a fact of life in the country.
If I read the tube at the point where the dot is mostly obscured, just a shadowy outline, I get a CYA of 60- a pretty big difference. Which one is right?
FC is currently at 13,
CC=0 (I hardly ever get a reading there, even when I cannot see the bottom of the pool),
Water is somewhat cloudy with a yellowish-green tinge and the bottom has lots of pollen/algae (probably both, pollen is a fact of life here). However, about 1/3 less than the day we took the solar cover off and did a thorough vacuum and backwash
My shock level depends on my CYA level, which I was taking to be 45 and was using a shock target of 16
Question 2: Do I need to do anything about the pH yet? Is that large of a jump common with shocking? When I was using Cal-hypo 65% to shock (a week ago) and with the solar cover still on, I only saw the pH go to 7.5, but I was shocking to 16- same level as now.
Picture coming shortly.