Does winter (midwest) impact CYA levels?

[Watermom]

However, if you "properly" close your pool by adding a large amount of chlorine to it, then the bacteria that consume CYA will not survive the chlorine. On the other hand, if you "let your pool water go South" by not adding chlorine to it, then you may get the sort of bacteria in your pool that consume CYA so that when you open up in the spring your CYA levels may be lower (but your pool will likely be full of green algae and need a lot of cleanup).

Then there are some of us who do close properly and who open to clear pools, (not green, no algae) and yet still have lost all the cya from their pool over the winter.

[chem geek]

Watermom,

Just curious, but was there a measurable chlorine level when you opened up your pool and found the CYA was gone? Perhaps the chlorine level went away, the bacteria ate the CYA, but it was too cold and not sunny for algae to form???

Richard

[Watermom]

Yes, I always have cl upon opening. This has always been the case for my pool. Always open to clear water.

[chem geek]

Great, another mystery to solve! Namely, how does the CYA go away over a winter closing when there is chlorine in the pool that should prevent bacteria from eating the CYA. Does the CYA breakdown due to the cold? Does this bacteria survive chlorine? Who knows?!

Thanks for the info.

Richard

[geordie]

I second Watermom. I open to clear water and chlorine. However, my CYA level is always significantly lower when I open than it was when I closed. This year I opened and had no measurable CYA at all. The pool is generally closed for 6-7 months out of the year and basically frozen for 3-4 of those months, depending on the winter.

Jean

[chem geek]

OK, I've made some progress in answering this. The PDF file accessed in this link describes how the key to degredation of CYA is an absence of dissolved oxygen. Ironically, colder water holds more dissolved oxygen than warmer water so that is counter to what happens in the winter when you close your pool. If the pool is covered, then perhaps oxygen gets used up in the pool. The article refers to chlorinated isocyanurates as sources of CYA so that would mean chlorine would be present and apparently this doesn't stop the degradation process. It seems that this process is catalyzed by biological processes (bacteria, fungi), but that just means it happens more quickly, so perhaps CYA breaks down all the time and that something about winter pools increases this rate.

So, do you both (Jean and watermom) cover your pool? Jean mentioned that the pool would get frozen; how about watermom's pool?

The reason I'd like to figure out exactly how the CYA gets broken down is that it might point a way towards reducing CYA in pools without a drain and refill (or waiting for winter).

Richard

[DerekM]

I am another one who opens with little or no CYA every year. Pool is closed in mid-October with a winter cover, is frozen several months, and, around May 1st, I always open to a clear pool, with little or no Cl and CYA. To reduce maintenance now that swimming days are scarce, I am running out the season with pucks, as I know from experience that whatever CYA I am adding will dissipate over the winter.

- Derek M
PEI Canada

[Watermom]

I usually do cover my pool, however, last fall my cover came off (with a little help from my two golden retrievers, but that is another story!) around the beginning of November. Since the bulk of the leaves had already fallen, I decided to just leave it uncovered the rest of the winter. My water remained clear and pretty clean. Here in south-central WV, my pool doesn't get much ice. Occasionally a glaze, but not a frozen pool by any means.