Back again with LOW CYA!!!

[lovingHDTV]

Looks like your CC is very high at 4.5
Your PH is low at 7.0

You need to adjust your PH back towards 7.6
Then shock the pool until your CC is <= 0.5
Then add CYA to get it back to 30-50.

You can use di-chlor for shocking, but it is more expensive that bleach and stabilizer last time I checked.

You could have been hit by what others are seeing on the forum where you FC drops to zero, then you CYA changes to CC. I've had this happen myself a couple times.

hope this helps,
dave

P.S. - the pool calculator can give you all the proper amounts.

 

[Butterfly]

First, use Borax to raise your pH (as it will have the least effect on TA).

Second, shock. You can use the granular to help raise the CYA. Go to Jason's Pool Calculator, near the bottom, to determine how much CYA will be added based on your choice of chems.

dave gave good advice

 

[chem geek]

You can use di-chlor for shocking, but it is more expensive that bleach and stabilizer last time I checked.

As I describe in Cost Comparison of Cyanuric Acid (CYA) Sources, Dichlor can be economical when one wants to add both chlorine and CYA. It's only more expensive if one wants the CYA without the additional chlorine.