Since the end of May, we have been unable to maintain a chlorine reading in our pool. Been getting the water tested at the pool store. Everything checks out ok, except chlorine is below 1. They tested for phosphates and said ours was "off the charts", so we have been putting in phosfree to deal with that problem. Finally got the phosphate reading below 100 and shocked with granular chlorine, but even one hour later, no showing of chlorine on the test strip. I took a sample to the store the next day and chlorine is below 1.
Readings from pool store Saturday:
C - less than 1 (don't know FC & CC)
Ph - 7.4
TA - 100
CH - 300
CYA - 60
Using Trichlor tabs in an automatic chlorinator
Found this site and used bleach last night. One hour after adding the bleach, the chlorine reading was in the shock range. This morning, no sign of chlorine.
Any ideas what is wrong?