CYA stays, right??

[y_not]

So I was reading Chem Geek's post in the following thread, it seems that chlorine does oxidize CYA? I thought that CYA doesn't deplete, it will only reduce from one of 2 things which require topping off, thus diluting it. Splash out, or backwashing.
Then of course the occasional algae or bacteria that'll eat it.

So what's the real story, the non-newb story?
Or does this only happen in the high heat environment of a hot tub?

softtub-manual-says-i-have-to-use-their-chemicals-t40722.html#p363254

"Just note that CYA slowly gets oxidized by chlorine so you may be losing around 5 ppm per month."

 

[chem geek]

At normal pool/spa concentrations of chlorine and pH the oxidation of CYA is slow. At higher spa temperatures it's a loss of around 5 ppm CYA per month when the CYA level is 30-40 ppm and chlorine levels are 2-4 ppm. In swimming pools, the usual CYA loss is lower due to lower temperatures, probably around 2-3 ppm per month. This is why we say that CYA doesn't get lowered except from water dilution because for practical purposes that is the only way to lower it in any reasonable amount of time.

If a pool is let go and chlorine levels get to zero, then bacteria can break down CYA, but this isn't well controlled and can result in a huge chlorine demand (or not -- depends on the mix of bacteria and whether they oxidize CYA to ammonia, nitrite, nitrate or nitrogen gas).

Some people report higher CYA losses during the summer with normal chlorine levels but we don't have an explanation for that unless there is something in the pool that is catalyzing (speeding up) the oxidation of CYA.

 

[y_not]

As I suspected it has to do with the considerably higher temps in the hot tub. That is compared to a pool, which is easily 30-35F lower.

In a pool in the winter time I presume you would loose even less? Being that the water is considerably colder than it is during the high heat of the usual 3 summer months; June, July & August.

 

[257WbyMag]

Yes, you would lose less during the off-season. That is, unless you let your FC drop to 0 ppm. No chlorine can result in a fairly rapid loss of CYA that is challenging to recover from.

 

[y_not]

Yes, you would lose less during the off-season. That is, unless you let your FC drop to 0 ppm. No chlorine can result in a fairly rapid loss of CYA that is challenging to recover from.

Referring to the mysterious algae/bacteria that eats CYA, right?

 

[257WbyMag]

Yep.

 

[chem geek]

As noted in Degradation of Cyanuric Acid (CYA), it's bacteria (not algae) and it's not mysterious at all and is well understood. It's just not easily controllable.

 

[WaterWizard]

It has a lot to do with Usage as well, plus you have a much different sized body of water. I have been on the spa end of testing water for customers and have not found CYA an issue. (considering your supposed to drain approx every 3-4 months bc of tds) with a regular use of oxidizer and a weekly use of Chlorine(shock).

On the first note I though that CYA was a mineral, which does not leave the water by evaporation. (meaning it does not turn into a gas?) Only by overflow, people taking it out on their bodies ,Draining and splash out.

 

[dmanb2b]

On the first note I though that CYA was a mineral, which does not leave the water by evaporation. (meaning it does not turn into a gas?) Only by overflow, people taking it out on their bodies ,Draining and splash out.

Welcome to TFP.

Feel free to search the forum...we have many documented cases of CYA converting over to ammonia and requiring a significant amount of chlorine to remedy.

 

[WaterWizard]

Thank you for the information I do love to constantly learn.

 

[dmanb2b]

Anytime...alot of good info in our pool school section as well (link in my sig). We appreciate your experiences as well.

 

[y_not]

As noted in Degradation of Cyanuric Acid (CYA), it's bacteria (not algae) and it's not mysterious at all and is well understood. It's just not easily controllable.

I only meant mysterious in reference to the statements that have been made as to the somewhat unknown nature of the bacteria that eats it. It has been mentioned that there is uncertainty as to where it actually comes from. The soil is potential suspect as to the source of it.
I have even seen one of the mods stating that if you can figure out what kind of bacteria it is, you could bottle it and sell it to remove CYA.
HA, good idea.

So that's what I was basing it upon.
So, misnomers, lies and allegations?

Thanks for the correction, I get algae and bacteria confused sometimes when it comes to pools. Not the obvious stuff of course.