CYA as a stabiliser

[pucklordofchoas]

So this is my current understanding, and im starting to think i maybe wrong, but currently we are perscribing customers with granular or liquid chlorine to use a dose of CYA stabilizer so protect the chlorine from sun degridations, is this correct?

and any thing you can tell me to help clearly define the role of CYA in pool chemical would be greatly aprecheated

[Backglass]

So this is my current understanding, and im starting to think i maybe wrong, but currently we are perscribing customers with granular or liquid chlorine to use a dose of CYA stabilizer so protect the chlorine from sun degridations, is this correct?

and any thing you can tell me to help clearly define the role of CYA in pool chemical would be greatly aprecheated

CYA = Cyanuric Acid, also known as Stabilizer. Sunlight degrades chlorine very fast. Without any CYA a pool can go from 10ppm of chlorine to zero in just a few hours. Think of it as sunscreen for chlorine. The target range is 30-50. Anything over 50 and you start having to maintain much higher chlorine levels to get anything done. Get over 100 and you start risking "chlorine lock" where even with high levels of chlorine it wont sanitize.

CYA is in all chlorine products that say "stabilized" like pucks, most pool shocks, etc. The only way to reduce CYA is through dilution...draining some water and refiling with fresh. To raise CYA you can purchase some or slowly raise it through pucks, etc.

Click for the Cyanuric Acid Wiki

[chem geek]

If you see an ingredient on a chlorine product that says "...trichlor..." or "...dichlor...", then that adds Cyanuric Acid (CYA) when dissolved in water. For every 1 ppm Free Chlorine (FC) introduced by Trichlor, you get 0.6 ppm CYA. For every 1 ppm FC introduced by Dichlor, you get 0.9 ppm CYA. Cal-Hypo does not add CYA, but it does increase Calcium Hardness (CH). For every 1 ppm FC introduced by Cal-Hypo, you get 0.7 ppm CH.

I don't believe in "chlorine lock". It's just that at very high CYA levels, you need very high FC levels and that can become impractical to maintain. Also, at high CYA and FC levels, the Trichlor tabs/pucks seem to take longer to dissolve, but that may just be my imagination and instead it may just be that the FC isn't high enough so algae forms and requires more chlorine (so more tabs). At really high CYA levels, above 150-200 ppm, plaster can be corroded (see this link).

Richard

[pucklordofchoas]

what about a lithium hypochlorite granular?

[chem geek]

That's a pure source of chlorine with no CYA and CH, just like sodium hypochlorite which is in bleach or chlorinating liquid. The only problem with lithium hypochlorite is that it is very expensive -- usually 5 times the price of Trichlor per FC (that is, per chlorine amount it adds to the water; not per pound). It is a quick-dissolving form of chlorine and is denser than bleach or chlorinating liquid so is less to carry around. If it weren't so darn expensive, it would be a very nice source of chlorine.

You can see a comparison chart of the cost of various chlorine sources, normalized to actual Free Chlorine amounts here.

By the way, for those customers that want to use bleach or chlorinating liquid but don't want the hassle of daily chlorine addition (unless they have a pool cover or have a pool not in direct sunlight), they might consider The Liquidator.

It sounds like you work at a pool store or are a pool builder (you refer to your "customers") and I want to thank you for getting educated about this. If you find this information useful, then you should let the manufacturers know since I've tried to work with some directly but they don't believe "real pools" follow the known chemistry, say of the relationship between chlorine and CYA and its affect on algae. They refer to a study they claim proves that only chlorine matters, but that study had hardly any green algae -- none in pools with no chlorine at all -- so something is very fishy about it. I talk about that here. Maybe they don't listen to me, but I think if pool store owners and PBs started demanding full disclosure then maybe we can get the education improved and also have some better "diagnostic" programs in pool stores that aren't just designed to sell more products.

Richard

[pucklordofchoas]

i actually work in a hot tub store, but there is no pool store in town so time and time again people come to my store with pool questions i tend to have no idea how to answer, hottub chemistry is similar but on a much smaller scale and me only use bromine as well the higher tempreture changes the playing field compleatly, but i thank you all for the wealth of information here it's been really helpful

[pucklordofchoas]

m next question would be, if your on a triclor or diclor granual, should you be adding stabiliser to the pool, as part of your sanitizing maintanence? or should it only be added when there is an adjustment needed