A few thoughts about CYA

In the 4 years or so that I have read the threads here, I can't count how many times newbies and veterans alike get into trouble with CYA levels. A question that has always been in the back of my mind is, why do we even bother using stabilizer in the first place? The common knowledge is that it protects the FC from being eaten by sunlight, and that by using it will save us the problem of 0ppm FC levels. If one tests their pool on a daily basis, like most here do, I would think that one would notice a low FC level and immediately correct it by adding more Chlorine. This, to me would eliminate the need for stabilizer. The problems this product causes seem to outweigh it's benefits. Chem Geek has graced us with his knowledge of these things. CYA inhibits FC's job of oxidation. Why would we use a product that effectively would strangle chlorine, just so the chlorine would be there after a days worth of sunshine? It just doesn't make sense to me anymore.

My pool, for example, under trees, is only in direct sunlight maybe 2 hours out of the day. We also swim in it almost on a daily basis. So, I can't help but wonder if the FC I lose periodically is due to swimmer load, or sunlight. I can never know, because I have always had CYA in the pool. I may not even need CYA since I'm only getting a few hours of sun. Since I have to keep a higher FC because the stabilizer is in there, it could be costing me more $ in the long run. I could be keeping a 1-3 ppm FC with 0 CYA, as opposed to the 6ppm I shoot for now with my 40 CYA. That first 1-3 ppm that's being held in a headlock could be free and ready for the battle, should it arise.:cool:

So here's the deal. Next season we are having a new liner installed. Since a full drain/refill will be done in the spring, I think I'm gonna try no stabilizer. I realize it's ways off yet, but it's something that has always bugged me, and I want to try it. I will, of course, post here my thoughts and results.

Thanks for bearing with my sort of rant lol:D

Cheers,

Ken

Hi, Ken. I think you'll have to do one of two things. Either add quite a large dose of chlorine to make you be able to make it through the day without losing all the cl to the sun. Or, add it several times each day which will probably be a big pain. Especially on days you aren't home throughout the day. If you do option #1 - large dose of cl, you may fade your liner or swimsuits. Just my thoughts. It is amazing how fast a pool with no cya loses all the chlorine. How well I remember that from my first summer I opened my pool years ago. Good to see you back around the forum.

Ken,

The problem is not CYA, but too much CYA relative to the Free Chlorine (FC) level (or conversely, too little FC for the CYA level).

Without any CYA in the water, the FC level in most pools will drop by 50% every hour around noontime in direct sunlight. In your situation with only two hours of sun, the FC might drop by 75% (assuming the sun is on the pool near noon in the summer), but for most pools what you propose is impractical unless one has an automatic dosing and measurement system.

Also, without any CYA in the water, normal FC levels are too strong and would oxidize swimsuits, skin and hair too quickly and produce more of the most volatile and irritating disinfection by-products such as nitrogen trichloride (see this post) and increase metal corrosion rates as well. The problem is that it is very difficult to maintain only 0.1 ppm FC in the pool (with no CYA) which would be a more-than-adequate level to prevent algae growth and kill pathogens quickly (the min. FC level in most of Ben's chart is roughly equivalent to 0.06 ppm FC with no CYA).

The CYA acts as a chlorine buffer holding the chlorine in reserve as needed so its use is much more than just protecting chlorine from breakdown from the UV in sunlight. The fact that it moderates chlorine's strength (i.e. the active chlorine, hypochlorous acid, level) is a good thing. In fact, I recommend that it be used, in moderation, in indoor pools -- at a level of 4 ppm FC with 20 ppm CYA to give a little more oxidation power in indoor pools since there is no assistance from UV in that case.

Every year, my wife experiences the difference of having CYA in our outdoor pool vs. swimming over the winter in a community center indoor pool with no CYA (and around 1-2 ppm FC). Her swimsuits degrade over just one winter season (the elasticity gets shot) and her skin is flakier and hair frizzier while in our outdoor pool none of these problems occur. Our pool has typically had around 3 ppm FC with 30 ppm CYA (it has an opaque electric safety cover) so is roughly equivalent to 0.1 ppm FC with no CYA. It's no wonder that with the indoor pool having 10-20 times the active chlorine level that the degradation of swimsuits, skin and hair was so noticeable.

Richard

CYA per say is not the problem, it's the misuse of CYA and the over use of stabilized chlorine products that cause problems. Proper use of CYA and stabilized chlorine is actually one of the best things that have happened to pool sanitation. Unfortunately, too many people use stabilized chlorine products improperly and run into problems.

Thanks everyone for the replies. And, Richard, as always your in depth knowledge reigns supreme and is greatly appreciated:D. Ok, so your saying that it would be nearly impossible to hold a steady FC level with no CYA in the water, even with only a few hours of direct sunlight on the pool. What would you suggest as a rock bottom minimum level the CYA be at in my case? The sun hits between 1 and 3 pm during June and July. May, Aug, and Sept, it's more like 1 to 1.5 hrs of sun. Could I get away with the numbers you would suggest for an indoor pool? Some of my curiosity lies in a possible savings of $ when it comes to chlorine. And, also in the possibility of increasing the FC effectiveness. Then again, if it only would lead to $20 to $30 savings a year, and leave me with nothing but frustration it's not worth it. I guess the saying, "if ain't broke don't fix it" comes to mind here. I may still try no CYA at first to see how it goes for a week or so. Like I said, it's a ways off yet, but since I'll have the opportunity in spring, who knows? :cool:

Thanks again everyone,

Ken

The indoor pool recommendation has a higher active chlorine level than you would need. Having even an hour or two of sunlight on the pool probably helps a lot in terms of UV breakdown of some organics (such as urea) and for airing out the pool for any volatile compounds. The minimum CYA would be 20 ppm though with your K-2006 test kit you can only easily measure down to 30 ppm so that would be the minimum.

So, 2 ppm FC with 20 ppm CYA or 3 ppm FC with 30 ppm CYA would be the minimum according to Ben's chart. However, note that your assumption that a lower FC results in lower absolute chlorine loss is wrong when a pool is exposed to a lot of sunlight. A pool with 8 ppm FC and 80 ppm CYA loses less chlorine than a pool with 3 ppm FC and 30 ppm CYA because CYA protects chlorine in a non-linear way shielding lower depths. However, in your situation with only 1-2 hours of sun, this effect may not be seen.

Also note that if you keep your water warm (88ºF), you may find a chlorine demand of 0.7 ppm FC per day even with no sunlight or bather load. So you want to make sure you have enough chlorine in the pool to not run out between your dosings. Having a higher FC and CYA gives you a larger chlorine buffer to protect you in case you miss a dose or when something unusual happens.

Actually, you might end up spending MORE on chlorine with lower CYA levels than higher. Also, there is some evidence that at levels around 60-80 ppm there is some evidence of additional sun shielding effects from CYA that are possibly physical in nature, much like a sunscreen so even though higher FC levels are needed they stay stable for longer periods of time and overall chlorine loss is less.

It will be an interesting experiment, should you choose to do it!! I think you're going to find that you actually spend more on chlorine without the CYA than with it, because you're going to have to dose it so high on a daily basis to make sure that you have a residual. And don't discount shocking--should you have an algae outbreak (and that could easily happen if you get lazy for even one or two days about adding chlorine), then over half of your chlorine put in the pool to fight the algae will be gone to sunlight. I'm not sure that you could ever sustain a high enough level of chlorine to kill off algae without some CYA in the water.

I'm no chemist, but from a practical standpoint, I just don't think it would work...

Janet

I'm almost scared to post.

I don't want to jinx myself.

We got a new liner this year and it became my job (instead of hubby's) to take care of the pool. Our above ground pool is 20x40.

As the water was filling, I found poolsolutions. :love:

I realize now that our previous years we had way to much CYA. The water was cloudy, the pool store said it was cloudy due to "organics" in the pool and to use clarifier "to sink them to the bottom in order to vacuum 'em up".

I found the BBB method and have used it all summer. We swim everyday. I check the water everyday. I add bleach every day. I haven't, however, added CYA yet.

This is the first year that our daughter's blonde hair isn't green.

Our bathing suits seem fine.

No algae blooms.

However, we are going on vacation and I plan on buying CYA to cover the absence of my daily care.

I guess I don't have an answer to your question. I'm just letting you know what I have done this summer.

I'd love to hear thoughts about this ...

What is your pool's volume? How many times per day are you adding bleach? How high are you taking the chlorine level when you do?

The pool is an above ground pool that holds ~21000 (I think it is 18'x39'). We had a pool party yesterday with ~12 swimmers and last night I added a gallon of bleach. I just tested it (the kids are already back in the pool) and FC=2 CC=0

Some stats: I'm in CA. Our elevation is ~3000'. We have a solar cover that we use every night; to get the water warm, to keep out the debris, and help keep the water level constant. I vacuum ~2 - 3 times a week. I run the filter (sand filter - 6way valve - if you need more details let me know, i'm not sure about the pump/filter) at night when I add the bleach and turn it off before bed.

Any other thoughts/questions?

According to my calculations, 1 gallon of 6% bleach in your pool should take you to about 3 ppm chlorine. Have you ever tested it again in the morning before the sun hits it to see what your residual is? Do you ever add bleach again during the day?

Janet

I haven't tested it in the am before the sun hits it, but I will and post the results. I do not add bleach until the evening, when we are done for the day.

I don't know the cost saving measures (yet) because in the previous years we were pool-stored and bought $$ chlorine there. So, compared to previous years we are saving money just by buying bleach at WalMart.

I will have to add CYA soon because of our vacation. I'd like to swim for perhaps a month more, but it won't be daily since the kids go back to school right after vacation and it will start cooling off at night. We are spoiled by our warm water!

I haven't had to add the other two B's, yet. Just bleach so far.

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Originally Posted by OddJob

I haven't had to add the other two B's, yet. Just bleach so far.

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If you are staying with unstabilized chlorine such as bleach you will need very little baking soda since unstabilized chlorine and lower TA is a more pH stable combination. Also, you would probably never need borax unless you actually overdose on acid when lowering your pH (unless you decide to add 50 ppm borates to your water for their algaestatic and pH control benefits, but that is a whole different thing).
The chemicals you are most likely to need are
Acid (either muriatic or dry)
Bleach (for chlorination and shocking)
CYA (stabilizer)

Just goes to show that pool care is REALLY as easy as ABC!;)

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Originally Posted by waterbear

Just goes to show that pool care is REALLY as easy as ABC!;)

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I agree!

I'm somewhat tempted to ask my parents to come by the house and add some bleach when we are gone and run the filter. And *not* add CYA ... what do you guys think? (I don't add bleach everyday ... if we aren't swimming, I'll check it at night and only add it if necessary. I haven't kept track, but it seems if we aren't swimming, I haven't had to add bleach). Therefore, if the keep an eye on it and add bleach every other day or so ...????

Sure. Why not. I can't imagine how you aren't losing all your chlorine to the sun every day. That is strange to me.

It's strange to me too, that you aren't losing all your chlorine to the sun, but if it's worked for you so far, then I don't see any reason to "fix what ain't broke". If they can add the bleach at the same frequency that you do, then I don't see where the pool will know the difference............;)

Janet

Hi there, I originally started this thread last week. I was thinking of trying no CYA next year after a full drain/refill after liner replacement. I was talking to a friend of mine down in AZ yesterday, and he was telling me I should consider bromine. He said he uses it and has had far less problems than when he had chlorine. He also said that bromine doesn't require stabilizer, and that CYA has no inhibiting factors to it. I told him that I thought they only use that stuff on spas and jacuzzis. HE said they do, but a lot of people use it for pools also. Would this be an alternative to bleach? Maybe just another crazy idea poppin in my head, as I am skeptical about it. Any thoughts?


Ken

advantages of bromine over chlorine in an outdoor pool:
1. none

disadvantages of bromine over chlorine in an outdoor pool:
1. cannot be stabilized against lost from UV light so chemical use is much higher and often there is no sanitizer in the water when it is needed most during the heat of the day because it has burned off (THIS is why bromne doesn't require stabilizer. It can't be stabilized! Hot tubs are kept covered to keep the heat in so they are not exposed to sunlight for long periods of time and indoor pools, well, obviously!)

2. more expensive requires more chemicals (sodium bromide to create the bromide bank, an oxidizer--usually chlorine, and bromine tabs, which normally contain organic bromide and an organic chlorine source.

3. bromine is a known sensitizer

4. Does not eliminate the use of chlorine since chlorine is the usual oxidizer in bromine pools. MPS can also be used but is much more expensive and MPS is also a sensitizer.

5. Bromine has a decided 'chemical' smell. Bromamines have a 'fishy' smell but are not eliminated since they are considered to be effective sanitizers, unlike chloramines. However there is some debate on this.

6. If pH drops low the formation of toxic elemental bromine is very likely and dangerous. Bromime tabs ARE acidic (like trichlor) so this is a possibility of you do not keep watch on TA and pH on a regular basis. I have seen it happen more than once!

There are some advantages in hot tubs and possibly in indoor pools (but indoor pools are also a subject of debate).

I still don't understand why you have this aversion to CYA. If you use an unstabilized chlorine and just add the proper amount of CYA to bring it up to 50 ppm you will not have any problems from overstabilization. Higher CYA levels can actually translate into less chlorine usage in many instances. The key is learning and understanding what you are doing and it's not really hard.


Also understand that I have a much better knowledge of bromine chemistry than the majority of people out there and have written guides for it's use on some other forums and have been quoted and referenced on at least one hot tub site (that I know of).
Also realize that lots of people using bromine are using it wrong (just like the number of people using chlorine that are using it wrong).

The key is education about the sanitizer you are using._

Hope this clears up some confusion.

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Originally Posted by OddJob

I'm somewhat tempted to ask my parents to come by the house and add some bleach when we are gone and run the filter. And *not* add CYA ... what do you guys think?

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As I posted before, you should have SOME CYA in the water, even if it's a low 20 or 30 ppm amount. Not having any CYA at all in a chlorine pool is bad on several counts. Not only will the chlorine break down in sunlight quickly, but it will be too strong unless you keep the level very, very low and that is pretty much impossible to do without automated dosing equipment and even then it's hard to maintain anything lower than 0.5 ppm FC reliably. So again, please add at least a small amount of CYA to the water.

Thanks for the info on the bromine. I really don't have an aversion to CYA, just am curious, really. Like I said earlier, if it ain't broke don't fix it. I will probably land up going back to my current levels after the refill in spring, since it's what's been working for some years now. Though maybe a little lower on the CYA (currently at 40). Maybe shoot for 20 or 30. What did they do in the old days before CYA? Must've had to check levels every few hrs during the day, is my guess. Anyways, thanks for bearing with my inquiries and maybe crazy ideas:D

Ken

As long as there have been Tri-chlor tablets and Di-chlor powder there has been CYA.

aylad, one of our moderators, keeps her pool at a very high CYA level, 80ppm usually, because in Louisiana, there is SUCH a high chlorine use she's be adding it 3x a day. At 80ppm, aylad maintains her chlorine between 5 and10 ppm and her pool stays clear and her chlorine usage is moderate.

This is what our "Ben's Best Guess" table is all about--correct levels of chlorine to use with various levels of CYA even up to over 100 (not recommended, but do-able).

CYA is a two-edged sword, but, with knowledge and a good test kit, you won't get cut by either edge.

This summer, lots of people around the nation have noticed much higher chlorine demand--myself included. Not sure why, but it just "is".

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Originally Posted by gordyjamz

What did they do in the old days before CYA?

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Good question. Historically, anhydrous ammonia had been used to stabilize chlorine since monochloramine is more stable to UV than hypochlorous acid. Sulfamic acid and sulfamates have also been used and, if I am not mistaken, so have hydantoins and other ammonia and urea like chemicals (which include cyanuric acid and cyanurates!)

It seems that chlorine/nitrogen bond that occurs has the main stabilizing effect against loss from UV light..

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Originally Posted by CarlD

As long as there have been Tri-chlor tablets and Di-chlor powder there has been CYA.

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The widespread use of chloinated cyanurates and the use of cyanuric acid did not really become widespread until the late 60s/early 70s but they were developed and introduced (by Monsanto if I am not mistaken) in the early 60s.

Ok. I just added 4lbs of cya. I put it in an old sock and hung it in front of the return jet. I tested and the black dot was *almost* invisible at 30ppm. I'm assuming I must be close to 30 since it is a definite change from no cya to this reading.

I'm not sure why I added it now ... since I've been good all summer (just lucky?). Vacation and ChemGeek have freaked me out!!

I will post a full set of numbers after we finish swimming. And I'll have to check the chart again and adjust my bleach addition accordingly.

ChemGeek, if you happen to read this far again, do you have any thoughts as to why I made it this far (since May) without CYA and no problems? I'm not being snarky, just curious.