A little background - I had iron stains in the pool and treated it Tuesday. Ascorbic Acid (Stain free treatment from the pool store) plus Aqua Coastal "Metal free". Did not quite lower chlorine, just added more of the Stain Free as I did not have time to bring chlorine down.
Had crystal clear pool till Friday. All readings were normal (using TF-100 kit):
Friday night pool got cloudy and little greenish - checked chlorine and it was at zero and PH down to 6.8. Added PH up (since TA is not too high) and 10L jug of chlorine Friday night. Saturday morning, pool looked more clear, but chlorine 0. Added another jug, chlorine 0. Another one, still 0. This morning - pool clear, but greenish. One more jug, chlorine still 0.
What is going on ? I never had to add more than a jug to maintain shock level.
Thanks for your help.