This is my first year with a SWG. It has been perfect. I live in the west burbs of Chicago. When the weather got cooler last weekend and less people in the pool, I thought it would be a good idea to turn down (from what I had set for the summer) the SWG from 20% to 10% and cut the pump time from 12hrs to 7hrs. FC had been at 5-7, CHY 70-80, PH 7.4 all summer.
Well, bad idea. After about 2 days, I noticed some translucent green algae on the bottom. I have 27' round AGP. Here are the numbers at the first sign of algae;
Per the pool calc, I added 2.5 gallons of 12% liquid chlorine, turned off the SWG, let the pump run. This brought FC to 28. After 48 hours FC is 22, CC .5. I have turned the SWG back on to help oxidize the .5 CC.
Water is crystal clear, no signs of algae on the bottom. I am a little concerned about the CC but the SWG should take care of it. But how will the FC get down to 5-7 if I am adding FC via SWG? 2nd, how could I have algae growing when the FC was at 3.5? Was this the effect of the SWG just not able to keep up at 7hrs/10%? There was still 3.5 FC?