Closing chemistry recommendation

[CarlD]

No. Use the lower value, I believe the left of the 2 columns. I do not recommend you closing your pool until any algae bloom is clear. Then raise to the lower shock level.
If your CYA level is below 10, use 10 as your shock level
Below 30, use 12.
Below 60, use 15,
Below 100, use 20,
100 or above, use 25.

[FormerBromineUser]

Last I saw was that your CYA was around 40 but were thinking about raising it. Did you? The number on the far RIGHT of the chart are only for mustard algae; extreme cases.

[amillionpets]

Last I saw was that your CYA was around 40 but were thinking about raising it. Did you? The number on the far RIGHT of the chart are only for mustard algae; extreme cases.

My CYA did raise, but it wasn't necessarily intentional. I began using Dichlor from Sam's in lieu of bleach. My CYA kept raising. I went back to bleach once it reached 70. Didn't want it to get any higher. So it stands at 70 as of today. I had a hard time keeping my pH down this summer. ??? Anyway, it's good at 7.9 now. TA=80. CC=0. Water temp is 45*.

Thanks for letting me know what the high shock level is used for.

[chem geek]

For every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases the Cyanuric Acid (CYA) by 9 ppm.

[FormerBromineUser]

Kinda makes you wonder why more people don't use dichlor to raise CYA instead of the slow-dissolving sock treatment!

[Watermom]

Kinda makes you wonder why more people don't use dichlor to raise CYA instead of the slow-dissolving sock treatment!

One advantage of using the straight CYA instead of dichlor is that is easier to know right off the bat the dose needed to get to a desired CYA level.

[JimK]

One advantage of using the straight CYA instead of dichlor is that is easier to know right off the bat the dose needed to get to a desired CYA level.

+1

I'm one of those who prefer to use straight CYA.

[amillionpets]

Yesterday 10:12 PMCarlD
Re: Closing chemistry recommendation

No. Use the lower value, I believe the left of the 2 columns. I do not recommend you closing your pool until any algae bloom is clear. Then raise to the lower shock level.
If your CYA level is below 10, use 10 as your shock level
Below 30, use 12.
Below 60, use 15,
Below 100, use 20,
100 or above, use 25.

Thank you, Carl. That's exactly what I needed. Leaves are still falling off of the trees here, and the temps are occasionally dipping below freezing at night. I'm not using a cover this winter. Too expensive just to have the wind rip it to shreds by the end of closing season. Nobody makes a cover that fits, or is meant to stay on, an AG vinyl sided Intex pool (that I can find) anyway.

I truly appreciate your quick response.