another cya dot question

[mariane]

My pool has a large drop in chlorine mid day ~ 4ppm worth. CYA reads 20 for sure, but maybe I can see the dot at 30. It seems I should add at least 10ppm of CYA so the sun is not burning off the chlorine.
If 20, then it gets me to 30. If 30 then it gets me to 40.
Would it make any difference which number I start with - 20 or 30?
Thanks!

 

[mknauss]

No really. Add 10 ppm CYA and see how it holds FC.

 

[mariane]

No really. Add 10 ppm CYA and see how it holds FC.

I didn't think so, so I'm glad you confirmed it. Thanks!

 

[Hootz]

You won't see much difference until you get to at least 50 cya. Try to slowly ease up to 50 as you add cya. It is easier to add a little at a time than overshoot and have to drain water. Wait 48 hours after adding to recheck level.