Opening Inground Pool - CYA Level Low

[Sastocky]

I am opening my pool today, *YAY!*, and tested CYA at <10. CYA was in range when closed.

Does the CYA stay fairly homogeneous or do I need to circulate for a while prior to testing?

Basically...start adding CYA or let circulate and retest tomorrow?

 

[Richard320]

Circulate, then retest.

Rule of thumb: always let the water mix about an hour before testing.

 

[Sastocky]

It mixed for 2 hours prior to testing.
pH 8.0
FC 0

 

[Richard320]

It mixed for 2 hours prior to testing.
pH 8.0
FC 0

Then it's pretty easy to get things straightened out.
1) Add acid to lower pH to 7.4ish.
2) Add CYA granules to raise CYA to 30ish. You can do this immediately after adding acid. Pay attention to the methods described in Recommended Pool Chemicals.
3) Half an hour after adding the acid, add the bleach you want. If the water is clear and the current CYA is 10ish, target 3FC. If it's green, target 10. Once some of that CYA dissolves, target 12. But that's all covered in the SLAM article.
4) When you have clear water and the CYA you added has had a week to dissolve, recheck CYA and raise it some more if necessary. You'll need to raise you target FC then, too.

 

[Sastocky]

Just read your reply but had already completed similar steps.

I was just curious if the CYA settles out or stays homogeneous.

I'm very surprised if it is this low as I do not drain my pool at all before winterizing, but I do have to pump quite a bit out when starting up. I've never had it drop that low.

 

[Sastocky]

Thanks for the advice! I'm amazed how many people you all help on here. Truly amazing.