I have an above ground pool about 13000 gal with a sand filter 1 and 1/2 hp the chlorine is high because I just added 3 gallons of chlorine and some alegacide the ph is at 6.8. The filter has been running since late yesterday afternoon I had put some alegacide in then. I back washed the filter before adding the chlorine and alegacide. It appears to be a cloudy green looking more. We fill from the city water. Not sure what a CYA no. is. Can you help me, I'm desperate.