Preparing the pool for a special event

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L

Linn

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Apr 19, 2016
69
California
CYA in indoor pool

Moderator Note - Split off from this thread: Liquid Chlorine vs Pucks, and Pucks without Stabilizer

Now our situation is somewhat different as we have an indoor pool and you should not use CYA for those. We use liquid chlorine (sodium-hypo) and it works very well. The only drawback is that the hypo raises the pH-value so we need to add acid to keep it down. But we've an automatic system that measures Redox and pH and adds the chemicals accordingly. It has worked great, the only problem right now is a problem with the pump for the acid.
 
Re: Liquid Chlorine vs Pucks, and Pucks without Stabilizer

Linn said:
Now our situation is somewhat different as we have an indoor pool and you should not use CYA for those.
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In your situation where you are using an ORP sensor to measure chlorine levels maybe, but indoor pools greatly benefit from a small amount of CYA to buffer the FC and create a much more comfortable swimming experience. We absolutely do not recommend against using CYA in an indoor pool.
 
Hi !

Right now we're in the planning process for a special event - we're hosting an after prom party when our oldest girl goes to her first prom. We were a group of parents that decided early on that we should organize some kind of safe after prom event to prevent the kids from going for the unsafe alternatives. As we have a pretty big house with an indoor pool, we agreed that we could have it at our place. Anyhow, we'd a meeting with the kids and discussed it all and they loved the idea, so it was easy to get them along. It will be an all-nighter but properly supervised so it won't go out of control. Especially we'll keep watch so we don't get gate-crashers or similar.

Anyhow, regarding the pool, we agreed that they couldn't very well be n the pool for many hours, so the first part will be dry (no use of the pool) and then the second part wet. We'd planned on the kids changing at that time, but then... teenagers want some extra thrills and the girls told us - hey no, just do it the fun, wild way - why don't we jump in in our prom dresses ? We've had kids parties earlier when a bunch of them have been in the pool with their clothes on and never noticed any trouble with the pool, but their ideas gave raise to another question - if they really want to do that, should we prepare the pool specially for that somehow ? They'll be super dressed up and I thought that maybe we could lower the chlorine some time before the party, as to reduce the risk of ruining their clothes ? But then one of my friends said that the chlorine level in a private pool is so low that it won't matter. Of course we must put safety before the concern about their dresses, the water may not get unhygienic or something. We normally keep the chlorine between 0.5 and 1.0 ppm, using liquid chlorine, and the pH at 7.6, with an automatic system. Any suggestions ? Anyone who's pulled off somethng like this and know how it works or who's got some good tips to spare ?
 
Why can't they be in the pool for many hours?

I agree with your friend, if you have the recommended FC levels for your CYA level, then the chlorine is very unlikely to damage anything.

Do you use CYA? If not I would highly suggest getting that level to 20-30ppm and then keeping the FC a little higher. I am afraid that without the CYA buffer, your 0.5-1ppm of FC will disappear VERY quickly with all the use and then the pool is not sanitized and safe.
 
No we don't use any CYA - it's an indoor pool and I've always heard that you should avoid CYA for indoor pools, for two reasons: 1) there's no need for it - no need to protect the water agains the UV of the sun 2) In an indoor pool you don't change the water very much. Not much dirt, no frequent backwashing., no winter draining and so on. If you use CYA it will eventually add up too high and you can't get it down again. Desides I don't think that liquid chlorine ever contains any cya, does it ?

The reason we thought they shouldn't be in the pool for many hours (all night) is that their skin would look like raisins afterwards... Temperature is not a problem, they won't get cld, we'll probably heat the pool a bit extra for this anyhow.Maybe around 88-90 or so ?

No most likely the chlorine won't be that hard on anything. But a couple of the moms thought it could be bad to their fancy dresses. It may be different in a public pool where there is a lot of chlorine , but possibly we're worrying about it for no reason.
 
You need some CYA to buffer the effect of the chlorine. While its not needed to protect from the sun, a small amount of CYA (10 ppm) will buffer the chlorine and make the pool feel better.

I would suspect the water alone may be bad for the dresses. The level of chlorine in a properly maintained residential pool should not have much effect on a dress or much less effect than the water itself.
 
This is a common misconception about what CYA does, you need CYA in an indoor pool to buffer the active chlorine, I keep mine between 20-30 ppm with the appropriate FC based on the CYA/FC chart Pool School - Chlorine / CYA Chart (20 ppm being the lowest reading on CYA test in the TF-100 test kit, the K-2006 test kit tube only reads down to 30 ppm, so I always suggest the TF-100 for indoor pool owners).

If you want the detailed reasoning Chem Geek has posted detailed reason why you need it in the past, or you can just trust me

p.s. CYA only builds up if you continue adding sources of stabilized chlorine, in general I check mine 2-3 times per year and adjust as it does slowly break down in chlorinated pool water, slow enough that people with outdoor pools don't tend to notice due to rain dilution, etc.
 
Hmm, how do you mean buffer the chlorine ? To prevent sudden changes in the chlorine level ? Remember that we have an automatic system, if the level drops fresh chlorine will automatically be added. Actually the system measures Redox, but I think that will have the same effect ? So far we've never used any other chemicals than chlorine and acid, except after our initial fill when we added a clarifier to take care of the iron that came with our water (we have a private well). If we'd use CYA would we use another type of chlorine or add that chemical separately ? The auto system can only hanlde liquid chemicals.

I guess that water alone can be bad for some dresses, but wouldn't that be pretty rare ? I got pushed in in my wedding dress at our wedding - it was supposedly dry clean only but it didn't suffer any damage from that. The main effect of chlorine (if any) would be to bleach colors, but since my dress was white that was no issue that time. But it was quite heavy to swim in ! :)
 
Chrissykr said:
The only thing I can add...They will have a lot of makeup/hair products/scents/lotions etc.

I have no idea what that can do to the chemistry. I am sure someone will be along that can help address this.
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I didn't think of this one, but I guess it would be hard to know that beforehand. On the other hand they won't be full of suntan lotions or oils like some regular swimmers. So far with our pool the hardest thing to clean has been if we get grease along the waterline - that does take some tough scrubbing to remove. We have tested with a high pressure unit - it was fast, took a good part of it off but didn't get it all.
 

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By buffer, we mean it makes the chlorine much less harsh and thus less damaging to skin, hair and clothes.
Shoot, I was going to show a chart, but the link is broken.
Basically in your pool with 1ppm of FC and 0 CYA, the water is {Edit: See more info in next post} at least 10 8 times harsher than if you have a CYA of 30ppm with a FC of 4ppm. (Hopefully I can resurrect the chart to prove this).

The CYA kind of keeps some of the chlorine in reserve. So with all the makeup and everything that will consume the FC, your 1ppm will be gone quickly, whereas if you had 4ppm (with some CYA), there would be more chlorine left to sanitize.

If you had CYA, you would not change anything with the other chemicals you use other than wanting to maintain the FC level higher. This does not mean that you will actually consume more chlorine though.
 
OK, found the link:
http://troublefreepool.com/~richardfalk/pool/HOCl.htm

That is showing the "active" chlorine level as a function of CYA on the left and FC across the top. This can be thought of as the "harshness."
So, for you current pool with a CYA of 0 and a FC of 1ppm, the active chlorine level is 0.484
If you added CYA of 30ppm, and kept the recommended FC level of 4ppm, the active chlorine level would be 0.060

So, without the CYA, your water is causing 0.484/0.060 = 8 times more damage to skin, hair, clothes, than if you followed the TFP recommendations.

If you wanted to match the harshness of the TFP water without CYA, you would have to maintain the FC level at about 0.13ppm ... that is just not possible to do consistently.

At a CYA of 30ppm, to have the water as harsh as your 0 CYA, 1ppm FC water, the FC would need to be to be up around 16ppm, which is higher than we ever recommend having the FC for a CYA of 30ppm even when fighting algae. See the FC/CYA Chart.
 
I know this is all new to you but please continue to read here and you'll see that 20 ppm or so of CYA is VERY helpful for your pool. Isaac-1 has been on this forum for years and years and has maintained a pristine indoor pool all the time. His advice is spot on the money. Jblizzle is one of our best technical posters.....his chemistry advice is always accurate.

I hope you continue to read more on the subject and get some CYA in your pool.
 
One possible concern here is if you are using a ORP probe to control your chlorine levels then the ORP will be effected by the presence of CYA and I am not sure if you can calibrate around that or not.
 
That is a good point, I am not sure at what CYA level the ORP starts having problems.

ANY CYA is better than none. Even if you just tried to do 20ppm, or estimated for 10-15ppm, the pool should feel so much better.
 
For most chemical sensing and automatic dosing systems, 30-40ppm CYA is generally recommend by the manufacturers as the maximum concentration before interference becomes an issue.

As mentioned above, 20ppm CYA would be very beneficial for your pool, not just for this event but from here on out. This low level should have little effect on your ORP readings.

What chemical automation system are you using?
 
Isaac-1 said:
One possible concern here is if you are using a ORP probe to control your chlorine levels then the ORP will be effected by the presence of CYA and I am not sure if you can calibrate around that or not.
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Maybe that was why the question was asked when we bought the automatic system whether our pool was indoors- or outdoors. Could it be that there are two version of ORP probes, dependng on whether you have CYA or not ? The probe is of course vital for our pool, it is that indication that will start or stop the pump that adds chlorine.

The automatic system is a real blessing. Both pH and chlorine are kept constant regardless of howmuch we are using the pool. We check with tablets now and then to see that the levels are ok, but as time goes by it's been less and less of that. We only measure free chlorine and pH though, we have no means of measuring things like CYA, alka, CC, calcium or others. But we've always had good water. The only problem with the water that we've had was when we first filled it up. When we added chlorine the water turned brown-greenish, as a result of iron that ame with out water. It got ok again after a few days of filtering plus adding some clarifier.

As for the party coming up, I don't think it will hurt the pool in any way. I guess the fact that they will be so dressed up is probably better for the pool than if they'd been in jeans. Jeans tend to give off a lot of lint, formal dresses won't do that. And should lint be a problem then all it takes is an extra backwash.The main thing is that they will be having fun and that we can keep them from going for something that could have bad sconsequences. Our daughter loves the idea !
 
I would highly suggest investing in a TF-100 test kit and more closely monitoring your chemistry, you will be amazed at how much better the water will feel and look if you follow our suggestions. I know I was when I switched to the TFP method 6 years ago.I never thought I had an issue before then either.
 
bdavis466 said:
For most chemical sensing and automatic dosing systems, 30-40ppm CYA is generally recommend by the manufacturers as the maximum concentration before interference becomes an issue.

As mentioned above, 20ppm CYA would be very beneficial for your pool, not just for this event but from here on out. This low level should have little effect on your ORP readings.

What chemical automation system are you using?
Click to expand...
I'm not sure of the brand, as the unit was bought (2nd hand) by the previous owner. However we bought new probes for it as the ones that he had bought had not been stored properly and had becme unusable. I know that the system is pretty old and came from some semi-commercial pool at some resort. It is not a digital system - it has two gauges with pointers and a small circle. The redox pointer should stay at the right hand edge of the circle. If it goes left a small bit the chlorine pump is tuned on. In the same way, if the pH pointer goes past the cente of its circle, then acid is added.
 
Linn, I want to address the girl's dreses.......Get some dark colored, silky fabric samples to throw in the water to show how they will react to the water. That will put the other moms mind at ease as far as the coloring. The boys on the other hand...do NOT let them take rented tuxes in!

I LOVE that you are doing this! I hope you have thought about the amount of food you are going to need!!! LOL

Now a word about what they will try (been there, done that) do NOT let them come and go....Once they leave they stay gone........They WILL have alcohol out in the cars and go out to sip on it :( Ask me how I know LOL

hugs! :hug:

Kim :cat:
 

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