I have a 27' round OB salt water pool. We had a really nice hot weather since I opened the pool at the beginning of July and easily maintained 3ppm FC and 0ppm of CC with the salt generator running @40%. The temperature never went below 80f. So last Wednesday night was the last time I took my solar cover off my pool because thursday was cold and friday we left out of town and only arrived Sunday night. Monday was a cool day so we didn't use the pool so the solar cover had been on 5 days.
This morning (Tuesday) I got up and took the solar blanket off and I vacuumed the pool but it was fairly clean with little debris and the water was clear but maybe not as crystal clear as it was a week ago but nonetheless very clear. I checked my chlorine and Ph with my taylor 2006k kit. I had 0ppm FC or maybe 0.2ppm as it had a very very slight pink color to it but I had 2-3ppm of CC indicating some sort of contamination. The Ph is 7.6 and the temperature was 74f. I checked my salt generator and visually inspected the cell and it was very clean except and little portion had some crystallization that I blew off mostly with compressed air. With the SWG in service you can see a slight cloud of chlorine like it did when it was new so I know that's not my problem. Then I passed my hand on the liner and it was slippery which indicates some sort of algae was in my pool. I brushed the floor and wall as best I could and shocked my pool with about 7L of bleach which brought the chlorine levels to about 7ppm measured after 3 hours or circulating.
How high should I raise the chlorine for a proper shock is 7ppm enough? I have 3L of bleach left that would bring the FC to about 10-12ppm, should I dump it in before I leave tomorrow?
The rest of my water tests as follows,
CYA 60 (I was due to add a little conditioner to raise this but didn't yet)
Did the solar blanket cause this algae outbreak? Someone told me that you should always take it off during the day so that the sun's ultraviolet rays can kill the bacteria that cause the algae? Is this true?
We are leaving again tomorrow Wednesday and only returning Monday, should we leave the solar blanket off the whole time? Should I leave the pump running 24/7 till we get back? We don't yet have a leaf net so there is going to be leaves in it for sure when we get back.