Water problems in small, small pool

We recently installed a spool - a very small (about 1500 gallon) circular pool to allow us to get out of the heat in the Arizona summers. As I suppose is normal for new pool owners who have never had a pool before we are having problems maintaining water chemistry and those problems are probably more severe because the pool is so small. Our chlorine levels were so high that we had to cut our tablets in half not to drive up our chlorine levels.

We started using the pool about 3 or 4 weeks ago and, when I tested the water yesterday, I found very high CYA readings (> 150) as well as high (= 150) Total Alkalinity readings. I have read that the best way to get rid of high CYA is to drain and replace some of the water, but my real questions are (a) how did our readings get so high to begin with and (b) is high CYA dangerous to people. Our chlorine reading is also a bit high (about 5) but that may be low with such a high CYA reading.

The pool place near us recommended that we add muriatic acid to lower our Total Alkalinity but our pH is 7.6 and if I add the acid I assume I will also lower the pH. I guess I don't know how to get the values into a reasonable range to begin with so I can then try to maintain them.

Any suggestions? Thanks.

Hi, Mike, and welcome to the Pool Forum!

Your high CYA is from those tabs which are presumably trichlor. High CYA will not hurt you but it will cause you to have to run higher than normal chlorine levels or you will constantly be battling algae. (Take a look at the Best Guess Chlorine Chart in my signature below for more about the connection between CYA and chlorine.)

If it were my pool, I would probably drain half the water and refill to try and lower the CYA level but that is only me. You may decide to just run the higher chlorine levels that will be needed. But, if you decide to do so, you will have to have a test kit that can measure chlorine levels higher than 5ppm which the Taylor K-2006 or 2006C will do. (Link in my signature.) In fact, even if you decide to do a partial drain, you should still consider buying that kit as it will make your pool maintenance much easier.

There is a guide to lowering alk. If you go to our sister website www.poolsolutions.com and click on 'guides' on the left hand side of the page, you will find directions for lowering alk. Also, please read the page about using muriatic acid safely.

First, thank you for your reply.

> Your high CYA is from those tabs which are presumably trichlor. High CYA will not hurt you but it will cause you to have to run higher than normal chlorine levels or you will constantly be battling algae.

In reading some of the water chemistry stuff I have seen I thought I saw something that said I should turn to non-stabilized chlorine instead of stabilized chlorine. If I do that, and if I watch my chlorine levels carefully, will the CYA levels drop? Or must I drain and refill? I ask because I live in Arizona and water is a precious (and expensive) commodity. Our pool is very small, but if I am constantly draining and refilling my water bills will not reflect the small size of the pool.

I will look over the guide you mentioned before I do anything. And thanks again.

Regardless of what you decide to do about doing a partial drain and refill or not, you must definitely switch to a non-stabilized form or chlorine such as bleach. No more trichlor tabs or dichlor shock powder. CYA take a long time to drop, so you are not going to see an appreciable change in it this year or maybe not even for several years. Having said that, in some pools, the CYA degrades over the winter into ammonia (which is another whole problem) but not in all pools and there is no way to predict in which pools this happens.

So, whether you partially drain or not, switch to bleach. But, you do need to order that good kit. Actually, even if you do a partial drain and refill, your CYA is still going to be around 75 or so and you will still need to be able to measure chlorine levels over 5, so go ahead and order it.

Let us know if you have more questions. We are glad to help!

> So, whether you partially drain or not, switch to bleach.

I am going to partially drain this morning although I will only start with a relatively small amount to see what effect it has. The pool store guy suggested about 6 inches of water but I am unsure why draining such a small amount will have an appreciable effect. I was never very good at chemistry at the University but draining about 10% of the water would not, I would think, cause more than a 10% change in CYA. And, as far as the chlorine is concerned, yes I am changing to non-stabilized right now.

> But, you do need to order that good kit.

Amazon lists both the 2006 and 2006C kits. The first is about $50 and the second is about $90, but it gives no information about the differences between them. Do you have any information? I don't want to spend more than necessary, but I don't want to spend less than necessary either. If the 2006C kit is worth the price then that is what I would want to get, but I have no information about why it is more expensive.

I assume, based on your response, that the high levels of CYA in our pool are not dangerous to us as people and are not dangerous to the pool provided I keep the chlorine levels commensurate with the CYA levels. Is that correct?

Thanks again.

You are correct in your thinking about the partial drain. If you drain half and refill with fresh water, your CYA level should drop by half. If you drain a fourth, the CYA level will drop by one fourth. In my opinion, unless you are going to drain a significant amount, don't bother because your CYA is still going to be high.

You are also correct that high CYA is not harmful but that you have to have higher chlorine levels as a result. The upside to high CYA is that you don't have to add bleach as often.

The difference between the 2006 and the 2006C is the size of the reagent bottles. The 2006 has .75 oz bottles and the 2006C has 2 oz. bottles which makes it a better price per ounce.

The "C" version of the K-2006 has 2oz bottles of reagent. The regular K-2006 has 0.75oz bottles. So you get more than twice as much reagent for less than twice the price.

> If you drain half and refill with fresh water, your CYA level should drop by half.

Thank you. That is the only thing that made any sense to me.

> The 2006 has .75 oz bottles and the 2006C has 2 oz. bottles which makes it a better price per ounce.

That makes the decision easy. If I am going to be testing daily then I am much better off with the larger bottles. Thank you again.

By the way, we keep our pool covered most of the day. That provides us with 2 benefits - the pool stays cleaner because leaves and other garbage is not falling into it and the water stays nice and warm and we can (probably) use it longer during the year since the water will still be warm enough to use in early Spring and late Fall. However I don't know how covering the pool affects the water chemistry. I assume that the chlorine in the water will degrade more slowly when the pool is covered because there is no sunlight to destroy it, but I don't know how the added temperature from the sun's warming the water in an "enclosed" space will affect what is happening chemically in the pool.

By "covered" I mean we have a pliable plastic cover that we drag over the pool after we are in it and remove before we enter it. Since the pool is so small (roughly circular with a diameter of about 10 feet) pulling it on and off is very simple and quick.

Will the chlorine levels drop more quickly if the pool is covered than if it is left uncovered? Or more slowly? Will not having direct sunlight on the pool surface affect the pH of the water? Or not? Will I need to watch and test more often or less often when the pool is covered?

The pool will lose chlorine a little less slowly but I don't think a cover or not will influence pH. I would suggest taking 5 minutes a day right now to test chlorine and pH. After a little while, you will learn what is normal for your pool and may be able to test every other day or so. For example, over the years I have learned that in my pool, the pH is very steady unless we get a lot of rain and then I know that my pH is going to drop and I'll need to add Borax. In time, you will see patterns in your pool as well.

Let us know if you have further questions. We'll be here to help!

I apologize for being so uneducated about this stuff. It seems as though I am asking question after question, but I can find no other place to get answers.

The most common statement I can find reading the descriptions is that I should use common household chlorine to maintain a proper chlorine level, especially if the CYA level in my pool is high (and mine is about 150ppm). But I can find nothing that tells me how much to add each day to keep the chlorine levels right. I know from the table that if my CYA is as high as it is I need to maintain a chlorine level of 5-15 ppm. But do I add chlorine directly from the bottle?

Do I dilute it first?
How much do I add at a time for a very small (1500 gal) pool? I don't want to drive the level too high.
How long does the chlorine level take to rise once the chlorine is added? How long before I should re-test?

Sorry, but all I seem to have are questions. I would appreciate any answers you can supply.

No need to apologize for asking questions. That is why we are here!

In your pool, each 1/2 cup of 8.25% bleach will add approximately 1.5ppm of chlorine. You can use that as a reference for how much you need to add each time you test. You do not need to dilute it. You can simply pour it slowly into your skimmer (if your pool has one which I think it does) or you can pour it slowly in front of a return jet, being careful not to splash it on you or the liner. That is it. Very simple. I typically wait 3 or 4 hours after I add before I would test it again but my pool has 18,000 gallons. In your pool, I think you could easily have it mixed in within and hour or so. Two to be sure.

It is best to test the chlorine and add bleach if necessary in the evenings after the sun is off the pool. With CYA at 150, you probably won't need to add it again for a couple of days. Test it the next evening and see where your chlorine is and then decide if you need to add more. If not, test again the next evening. You just want to make sure you can make it through the next day without ever dropping below your minimum based on your CYA reading.

Don't hesitate to ask more questions if you need to. That is how you learn. (Does that sound like a teacher?? ;);))

OK. That is very helpful. From what you have said I should be checking and adding daily since bleach will dissipate rapidly.

But what do I do if we are gone for a week or two? If I add the chlorine tablets, which will maintain a chlorine level while we are gone I assume I will just drive up the CYA levels even more. If I use bleach before we go the chlorine level will drop to 0 since no one will be adding it during our absence. Is there an alternative such as bleach tablets which would dissolve slowly?

Thanks again

Here's one option:

Super-simple-pool-chemistry-recipe-for-Intex-type-pools-start-up-amp-routine-care.

EDITED TO REFLECT WATERMOM'S POST BELOW.

Recipe above applies only if you drain and refill. I misunderstood, thinking that you'd already decided to do so. For an 1800 gallon pool, that's what I'd recommend. It's not worth saving the water, for the amount of tweaking you'll have to do.

Mike,
I think PoolDoc may not have read through your thread. You do NOT want to use that recipe mentioned above. It is meant for pools that have a fresh fill with no CYA in them yet. In your pool, you do NOT want to use dichlor as it will add CYA and you definitely don't want that!

If you are gone, do you have anybody who can come by every 2nd or third day and add some bleach? I think you will find after you test for a week or two that your pool isn't gonna need chlorine added every day. So, if you can hire a neighborhood teenager or whatever to come by a few times a week and add a pre-determined amount of bleach and clean out the skimmer basket, that is probably your best bet. If you really don't have anybody, you can use some of the pucks for a few days, but, yes, they are going to push your CYA up and your pH down.