Year old above ground pool, gunite, screened in FL. Water chemestry good.. PH 7.6, Salt 3600, CYA 80, Phosphates almost 0, Alkalinity 100, Calcium 70, Nitrate 0. But chlorine at 0 even at 100% output for 8 hours a day with IC 20. This is the 3rd unit from Pentair in a year!!! First one died after 8 month, second was tested to produce at dimished capacity. It seems I have a huge chlorine loss. I have to add liquid chlorine ( gallon) every other day. It is a mystery so far to all people I spoke. BTW.. water temperature is 80F, air temperature 83 F. No pool use in about a week. After adding gallon liquid chlorine during day... get up to 4ppm, but next day mid day is at 0. The IC 20 is still running even I add chlorine. Can somebody help me please? What can cause such a huge chlorine loss? Is the 3rd unit I got also bad? Why can I not generate chlorine? BTW. the unit is only 3 weeks old and clean. PLEASE HELP!!