A few thoughts about CYA

[waterbear]

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.

[gordyjamz]

Thanks everyone for the replies. And, Richard, as always your in depth knowledge reigns supreme and is greatly appreciated. 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?

Thanks again everyone,

Ken

[chem geek]

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.

[waterbear]

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.

[aylad]

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

[OddJob]

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 ...

[Watermom]

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?

[OddJob]

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?