So you may have seen my posts back in December where I had to leave for 3 weeks. I raised my FC level to 16.5 ppm and added acid to get my ph back to 7.4 before I left. I also put 5 Trichlor tablets in the inline chlorinator and set it to the setting that normally applies 1 tablet per week. The pump runs 10 hr/day and I turned the solar heater off plus I left the suction pool cleaner hooked up and set to stay only on the bottom. I was pretty concerned I'd have a green pool (meaning green water not just algae on the walls) when I got back. I was able to view the pool on a security camera while out of state and to my surprise the pool color stayed clear and the walls only built up a very thin layer of green algae on the walls that were in afternoon sun. And get this. The pool chemistry is almost perfect! (see my test results below). So I cleaned the filter (not especially dirty but it did have some green algae at the bottom. Most of the media was white or barely off white.
I was expecting the worst and I'm guessing the explanation is that my FC stayed high enough to keep the suspended live algae in check and as the individual cells died they clumped then got trapped in the filter. And I guess the pool would go green completely if I let the FC drop far enough. I plan to scrub in the morning and filter during the day then go back to my normal TFP routine as the FC drops to normal levels for my low CYA level. And I'm thrilled that the CYA level did increase about to levels predicted by the Pool Calculator. The only thing I can't really explain is why the algae on the walls stays alive (or at least the contained chlorophyll stays in the cells).
Date TA CYA FC CC CH PH Actions/Observations 15-Dec-15 70 20 5 0 300 7.5 Added 4 oz Muratic early morning, tests 5 hrs later 16-Dec-15 Added 192 oz 10% Cl 17-Dec-15 16.5 8.4 Cleaned Filter, Addded 16 oz muriatic, 40 oz trichlor, Chlorinator 1.5, noon ph 7.4 18-Dec-15 Gone but pool water clear 19-Dec-15 Gone but pool water clear 20-Dec-15 Gone but pool water clear 21-Dec-15 Gone but pool water clear 22-Dec-15 Gone but pool water clear 23-Dec-15 Gone but pool water clear 24-Dec-15 Gone but pool water clear 25-Dec-15 Gone but pool water clear 26-Dec-15 Gone but pool water clear 27-Dec-15 Gone but pool water clear 28-Dec-15 Gone but pool water clear 29-Dec-15 Gone but pool water clear 30-Dec-15 Gone but pool water clear 31-Dec-15 Gone but pool water clear 1-Jan-16 Gone but pool water clear 2-Jan-16 Gone but pool water clear 3-Jan-16 Gone but pool water clear 4-Jan-16 Gone but pool water clear 5-Jan-16 Gone but pool water clear 6-Jan-16 Gone but pool water clear 7-Jan-16 Gone but pool water clear 8-Jan-16 70 30 7.5 0 300 7.7 Pool water clear green algae on afternoon sun walls. About 3 Trichlor tabs consumed