Was away for 1.5 weeks and I return to a very white Ė canít see the bottom - cloudy pool. I have an automatic vinyl cover which was closed and a SWG that I havenít had to touch all summer and have had crystal clear water since May. The SWG normally maintains a FC of 3.5 ppm. Pump runs on a timer from 8am to 11pm so 15 hours of run time per day.
I was kind of surprised that I had an outbreak seeing as it was completely covered, but we did have the hottest days of the year while I was gone +/-95 deg F. The cover tends to heat the water to a couple degrees below ambient, so Iím guessing the water temp was in the high 80ís low 90ís for a few days while I was gone.
Question 1 Ė With FC of 3.5 ppm, cover closed, 15 hours of pump run time, would the elevated water temp be enough to allow algae overpower the FC level? I also thought that with an opaque cover, there would be very little light to support the algae growth? Thoughts?
All of this said, Iím slamming the pool with Chlorine. Started yesterday morning with powdered shock b/c I know my CYA is low, as in Zero and thought this would be a good way to add CYA. I started with 3 bags (lbs) at 8am, then tested FC levels and added 3 more around lunch, then tested FC Levels and added 3 more around 4 oíclock. Each time i tested the FC was 0. At this point I switched to Clorox and have added to date 19 Ė 121 oz bottles of Clorox which is 8.25% Sodium Hypo. Thatís 2300 oz of chlorine on top of 9lbs of powdered shock. I started registering FC after the first 6 jugs of Clorox. Iím slowly getting there, today I am maintaining FC 2-5 ppm above the slam level so its just a matter of time now. Iíve been backwashing frequently, keeping the cover on, and should start to see progress soon but it is still cloudy.
Question 2 Ė Does the automatic cover let in enough light to degrade the Chlorine? Iíve been testing pretty much on the hour and the FC is always dropping 2-3 ppm. I believe that the chlorine is still working on lingering algae growths, but in the back of my mind I just wonder if the cover is truly opaque.
Levels as of 1 pm today
I just added two jugs after these readings, so Iím hoping the next time I test FC, it should be around 18-20.