Cya Control

[Rocks911]

I've had an inground pool to take care of for the last couple years and CYA is my primary nemesis. How does one go about keeping it at a reasonable level?

The first year or two I thought to myself as I was dumping large amounts of granualar chlorine into the pool, "hey theres nothing to this" then I discovered the problems with high CYA as I couldnt keep algae under control. I drained the pool, power washed it and refilled it last year. I have used granular very cautiously since but today I tested the water and my CYA level is at 55+. Before summer gets here I need to find a solution to keeping the pool sanitized without having a CYA problem.

Is there a commercially available chlorine source that doesnt have CYA as an integral component?

How do people manage to keep CYA levels under control? Here in Dallas apparently we dont get enough rain to wash CYA out of the pool and regular backwashing doesnt seem to do it either, so how do I manage this?

[PoolGuyNJ]

Bleach. Clorox is 6% and chlorinating liquid is 10 to 12%. The rest is salt water. Very benign to a pool.

Trichlor tabs all have CYA. Some brands add copper sulphate as an algaecide but can cause green staining.

Dichlor powder has even more.

Cal-Hypo adds calcium, a scale producer if you don't watch your chems. This would yield similar needed actions to excessive CYA in that the only way to get rid of it is via dilution or a reverse osmosis service.

Scott

[FLPoolGuy]

Don't overload your pool with tablets in the cool months when you don't have the effects of the sun. Here in Florida we almost completely discontinue use of tablets during winter months because we don't have the degrading effects of the sun and we get very little rain to dilute the stabilizer. 55 ppm isn't a bad level to maintain, however here in Florida commercial pools can not be higher than 40 ppm in pools and zero in spas.

[AFiremanFirst]

55ppm of cya in Dallas is great in Feburary, but in July you'll have trouble keeping chlorine in the pool. I wouldn't adjust 55 down in Dallas, I'd adjust it up!

First off this is a highly debated topic. I manage 32 pools in the North D/FW area. 80 seems to be a common number people like. And folks up north would die if they saw 100 ppm of CYA. But last year with 35+ days of 100 degree + weather... 80 won't work. Remember that 100 degree weather forecast is temperature in the shade, not on your pool deck! Our water reached 94 degrees and stayed there for quite sometime last year. What you should be concerned with is that you maintain at least 5% chlorine for your CYA ie 5ppm of chlorine to 100 ppm of CYA. Keep in mind few swimmers will notice chlorine below 30ppm, burning of the eyes is most often the cause of an imbalanced pool... pH, alk, calcium, etc.

I don't disagree that we often too in dallas don't worry so much about chlorine in the winter months, but with our unseasonably warm winter I suspect you either do have chlorine in your pool, or you have algae! For those who don't know... Unseasonably warm winter for dallas is no snow, no ice, and only a few days where we dipped to 27 for less than a few hours. Our water has been at 50 degrees for some time now too.

I agree with Scott! The dichlor he is referring too is likely sodium dichlor which is what most of our local pool stores are going to sell to you. Seldom do they push Cal hypo (calcium hypochlorite) why? Because our tap water has 120ppm of calcium! Throw in all the evaporation we fight and you can see that your calcium jumps rapidly, which leads to scaling.

IMHO the answer to your question, "how do we control CYA"? Is we supplement liquid chlorine. 6% bleach is sold at your local wal-mart for $0.85 for 3/4 of a gallon. This is the cheapest form of chlorine avavilable to you!!! I use a commercial based bleach which is 12% and I'm sure you can find it locally too if you'll do some leg work.

CYA is a menis in dallas, but it is usually due to the chlorine demands of our pools and the over use of trichlor tabs. We have long hot summers/swim seasons. We use lots and lots of Chlorine. But Calcium is most often our menis as our tap water is so rich in calcium and we have so much evaporation. Liquid bleach is the solution to your problem. But I encourage you to raise your CYA. And to FLPOOLGUY's point I believe our commercial regulations are 35ppm, but remember, those are tested daily!

[chem geek]

There is a pool service in the desert regions (southern California, Arizona, Nevada) that uses 100 ppm CYA in their pools in order to reduce the chlorine loss in such hot sunny areas since they only visit the pools once a week dosing with either chlorine gas or sodium hypochlorite or a combination of the two. Dosing up to 14 ppm FC has the pool at around 4 ppm FC when they visit a week later. For a homeowner manually dosing more frequently, one would want to keep the FC at a target of around 7.5 ppm or so. The active chlorine (hypochlorous acid) level is a function of the FC/CYA ratio so even 10 ppm FC with 100 ppm CYA is the same as 3 ppm FC with 30 ppm CYA and is the same as 0.1 ppm FC with no CYA so far less than chlorinated tap water. Having a high CYA level is not a problem if one maintains a proportionately high FC level. Just note that IF one lets the chlorine level drop too low, then shocking the pool to recover requires a lot more chlorine at the higher CYA level.

[waterbear]

Don't overload your pool with tablets in the cool months when you don't have the effects of the sun. Here in Florida we almost completely discontinue use of tablets during winter months because we don't have the degrading effects of the sun and we get very little rain to dilute the stabilizer. 55 ppm isn't a bad level to maintain, however here in Florida commercial pools can not be higher than 40 ppm in pools and zero in spas.

Where in FL? Unless things have recently changed C?YA is allowed up to 100 ppm. However, Pool and spa sanitation is under the control of the local health depts so it may be different in your area.

[AFiremanFirst]

And I agree. Nice though that in the desert it cools off at night, in my region we are not so lucky! Update... I check with the guys maintaining commercial pools in my area. 100ppm is common (regulated by each city differently).

[PoolGuyNJ]

What is allowed in commercial pools and what is allowed in residentials will likely be two different animals. Most residentials will allow anything while commercial facilities will have specific rules in place and likely for specific reasons. In NJ, for the most part, commercials are allowed CYA but iti is limited and usually has some sembelence of common sence while in NYC and Nassau County NY, it isin't at all. Local rules apply.

If a facility uses tabs, CYA buildup can be an issue. My local facility that uses tabs is an indoor facility that also drains their pool anually. This allows any work to be scheduled in addition to refilling with fresh water. That would be a problem in drought areas like Southern Texas has now. They are pretty much forced to use liquid to avoid CYA can calcium.

As for treatment, there are only two ways I know of, dilution and reverse osmosis, the latter only being available in the San Diego area.

Scott