Why Is Cya Such A Contentious Issue?

[Dietitian]

A friend of mine, who is a pool maintenance guy and very intelligent, believes CYA use in spas is not a good idea. He has read the 1974 report on CYA, but is so bored of arguing the CYA issue (apparently with other pool guys) that he doesn't want to get into it with me.

He thinks that chlorine is never a good idea for an above ground spa, with or without CYA, and that I should switch to bromine and leave out the CYA.

I'm wondering why he is convinced that CYA and chlorine for spas is unacceptable, when everything I've read here (mostly from chem geek) has indicated that CYA is great for hot tubs and helps to regulate the strength of chlorine and reduce damage to the tub cover, bathing suits, etc.

I can't figure out what the other side of the argument might be -- is it a concern for safety in terms of bacteria growth? Is it a blanket recommendation because most spa owners are irresponsible with testing/maintenance? Do most owners put too much CYA in the spa?

[chem geek]

Ironically, your friend's advice runs counter to a spa industry that largely promotes Dichlor-only use for spas that obviously increases CYA levels to very high amounts. At the other extreme is what your friend is saying and what many commercial/public spa regulations say which is not to use any CYA at all in spas (or in indoor pools). For spas, the argument is mostly that there is no sunlight so no need for CYA, but that is an ignorant argument that ignores the moderating effect of CYA on chlorine. There is also the argument that spas need a higher level of sanitation, but how high is really required? With no CYA at all and with up to 5 ppm FC, the active chlorine level is at least 8 or more times higher than what exists (in a hot spa) with 4 ppm FC and 30 ppm CYA.

I don't know what to tell you. If your friend understands chemistry, then you should find out more specifically why CYA should not be used. Does he have evidence for a specific level of disinfection needed that requires such higher active chlorine concentrations? I would be interested to know his concerns and reasoning. Maybe there is something I don't know about that would swing the argument his way in spite of the side effects.

As for most owners putting in too much CYA, the answer is clearly yes since Dichlor-only use at 4 ppm FC per day results in over 100 ppm CYA added every month.

This issue of chlorine and CYA isn't just with spas, but also with pools and the industry is pulled by extremes where the stabilized chlorine manufacturers say that CYA doesn't really matter, that no outbreaks have been correlated with high CYA levels, etc. At the other extreme is the CDC and others who see Crypto not being able to be inactivated even by shocking when there is too much CYA in the water so as far as they are concerned CYA shouldn't be used though they are practical about this and just say to keep it low. There seems to be very little pragmatic discussion by people in the industry and government regarding setting a reasonable sweet spot that balances disinfection and algae prevention against side effects including disinfection by-product production or degradation of materials. This is not only due to the economics of fiduciary responsibility to shareholders (which doesn't care about health; only profits) but also to the specialization of scientists where the bacteriologists and epidemiologists don't really know detailed chemistry very well and the chemists don't really know biology very well.

And then there's me who has no credibility at all, but try to straddle multiple disciplines since I'm only interested in the truth, the whole truth, and nothing but the truth. Of course "truth" is not absolute, but where the industry is at now is far from anything resembling truth. The pool and spa industry in terms of misinformation seems to me second only to the supplements (vitamins, etc.) industry. The amount of B.S. and scare tactics and either misleading, incomplete or just plain wrong information is astounding. Fortunately, there are those who do tell the truth, who do listen and learn, and who do want to sincerely help people and not just fill their wallets. You will find many such people, including many dealers and industry folks, on this forum. There is hope and I sincerely believe that this situation can improve over time.

[Retep]

The pool and spa industry in terms of misinformation seems to me second only to the supplements (vitamins, etc.) industry. The amount of B.S. and scare tactics and either misleading, incomplete or just plain wrong information is astounding.

I second that

The other day I happened to listen to a conversation what a sales guy at the local pool/spa store told a client who brought in a water sample. . . .

Next thing you know the client got talked into buying stuff which boggled my mind.

I guess its all about profit and sales people at the stores are pressured by the owners to sell as much / many chemicals as possible.

[OttawaGreg]

A friend of mine, who is a pool maintenance guy and very intelligent, believes CYA use in spas is not a good idea. He has read the 1974 report on CYA, but is so bored of arguing the CYA issue (apparently with other pool guys) that he doesn't want to get into it with me.

He thinks that chlorine is never a good idea for an above ground spa, with or without CYA, and that I should switch to bromine and leave out the CYA.

I'm wondering why he is convinced that CYA and chlorine for spas is unacceptable, when everything I've read here (mostly from chem geek) has indicated that CYA is great for hot tubs and helps to regulate the strength of chlorine and reduce damage to the tub cover, bathing suits, etc.

I can't figure out what the other side of the argument might be -- is it a concern for safety in terms of bacteria growth? Is it a blanket recommendation because most spa owners are irresponsible with testing/maintenance? Do most owners put too much CYA in the spa?

So going the bromine route for sanitizer does not require or add to CYA?

Greg

[quantumchromodynamics]

...he doesn't want to get into it with me

I'm wondering why he is convinced that CYA and chlorine for spas is unacceptable,

I can't figure out what the other side of the argument might be -- is it a concern for safety in terms of bacteria growth?

Dietitian, my advice is to ignore people who don't want (or aren't able) to explain their reasoning for their advice. If he has a legitimate argument, he should be able to give some sort of logical explanation.

[chem geek]

So going the bromine route for sanitizer does not require or add to CYA?

Bromine doesn't require nor add to CYA. Bromine tabs do add to DMH though it is not clear how much of an effect it has on bromine effectiveness at levels that it builds up in spas.