Chlorine reading of 0 after dumping 10 gallons of 12% chlori

[iskubits]

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):
TA 60
FC 7.5
CC 0
PH 7.5
CYA 40

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.
Igor.

 

[JasonLion]

Re: Chlorine reading of 0 after dumping 10 gallons of 12% ch

That is normal after an AA treatment. It often takes a while before the pool will hold chlorine. Any leftover AA from the treatment will combine with the chlorine you add and destroy both as quickly as you add chlorine until you finally overcome all of the leftover AA. This can be especially dramatic if you used a lot of AA.

 

[iskubits]

Re: Chlorine reading of 0 after dumping 10 gallons of 12% ch

Thanks ! I guess I am off for another 5 jugs

Just wanted to make sure I am doing the right thing by adding more chlorine.

Igor.