Low CYA every year...

mailmanic

Member
Jun 4, 2018
14
Massachusettsdd
35,000 gallon in ground vinyl pool, SWG

A few years back this forum helped me realize low CYA was my major problem (0-10 CYA in a Salt Water Pool). Once I got it up to 70 using the sock method I have a crystal clear pool that's very easy to maintain all season.
My problem is the low CYA happens every year, and I have to go through all the trouble of adding stabilizer in the sock method for days until I get to 70. What could cause loss of CYA every single year? Why does my CYA stay perfect in the open season but deplete over the winter/spring?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,851
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
CYA degrades over time and the amount can vary. Over teh course of 4-5 months perhaps 15-20 ppm. I suspect you also lower your water level for winter which will contribute to that loss. Add to those the +/- 15 ppm variance in the CYA test and you can find yourself adding stabilizer each spring.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,851
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Thank you for helping me understand! I'll have to stock up in stabilizer each year to save some time.
It's a weird thing sometimes. I've had some seasons where my CYA almost never drops, then some periods where all of a sudden I lost 20 ppm and I'm stunned. :scratch: I also had one season where one particular brand wouldn't hardly register after adding it. The good thing is having the ability to catch those issue with a proper test kit as you just did. :goodjob:
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,562
NY
Hey Mailmaniac !!! Don’t go postal here. We get about 3 ft of off season rain each year. If you don’t have a completely solid cover, it’s more than a 50% free water exchange with an average depth for most at 5.5ft. My looplock cover appeared solid, you could hold it up to the light and not see through it, but the 98% mesh still let all the water through, just slowly. A saturated tarp would be similar.

Factor that with the 4-5ppm CYA degrades on its own each month and most of us up here close at 70 and open with 0-20. It’s almost unnoticeable month over month during the season, Maybe you need a mid summer top off, but when you close and walk away for 5 or 6 months, It adds up.

It’s a GREAT problem to have. You get a decent reset each winter and it makes your summer that much easier to keep the CYA and CH in check. Many have no choice but to drain when they get high and Mother Nature throws you a freebie each year.
 
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