CYA level after long winter

Bordertown

Active member
Jun 19, 2018
41
Nova Scotia
would CYA be all gone after 8 months of fall & winter ? I was at 60 when I closed the poll. 2 days ago I added 77 oz, that should have gotten me to 30 ppm so that I can start the SLAM process.
However I'm reading like 50 today. Or is it too soon to get a proper CYA level reading? I did dissolve in sock in proper method, brushed, PH @ 7.4. I'm just concerned that the current slam level of 12 may not be accurate if CYA is indeed more that 30. No I did not take a reading of CYA level before I started, my bad.
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
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Liquid Chlorine
48 hours after it's all dissolved should be enough time to get a good reading. If you're reading 50 on the CYA test, then SLAM at 50 CYA, and not 30. You might have had some residual left over from last year - it doesn't all go away each winter, typically.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
11,174
Franklin, NC
CYA does not generally go away. Maybe 1 - 2 ppm per month. If you closed with 60 I would have expected most of that to still be there.

I'm sure you have at least 50, if not more.
 

IceShadow

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TFP Guide
Jun 8, 2019
2,612
Milwaukee, WI
Pool Size
20000
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Vinyl
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My CYA has been 0 at the last two pool openings when closing with 40 or so the previous year. I don't know why. I have a mesh cover, so my best guess is that the bacteria that eats it into ammonia was in the pool and converted it, but since it's only 40ppm or so further diluted by emptying below the returns and then rain/snow refilling, the initial chlorine I add at startup gets rid of it.
 

Bordertown

Active member
Jun 19, 2018
41
Nova Scotia
happy to report Slam was successful, waiting for FC to drop below 10 and raise water temp so we can swim this coming weekend. Every year I lean something new about pool chemistry....hopefully it wont always be the hard way lol. Summer begins :)
 
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