CYA level and chlorine level and pool store recomendation

[Fishcrazy]

Hi and thanks for a great forum. I sure am lucky to have found it as I am a new pool owner and knew nothing at all about pools and water chemistry before now and what I do know came from this forum. I have a 27 foot round above ground. My latest water test from the pool store is as follows. TC 2, FC 2, pH 7.2, TA 120, CH 200, CYA 60. The pool store has sold me a lot of supplies and they of coarse recommend treatments which I have initially followed due to lack of any knowledge to the contrary on my part. So here is what they have had me do so far. I initially shocked the pool with some granular product and added algecide and stabslizer. They wanted me to add 12 pounds of stabilizer to the pool an I decided to add only half of that to see what it produced after it got in the water. A CYA of 60 is what we got. Now at that level they are recommending that I keep the FC at 2. I have been using the pucks they sold me to chlorinate with and I know that that adds stabilizer to the pool as well. I would expect the level of CYA to rise going forward using these pucks and therefore requiring more chlorine with these higher CYA levels. At current CYA levels I should be at higher FC level than I am now according to the BEST GUESS chart. My delima is that the pool store product doesnt recommend on their lable that swimmers use the pool above a FC of 2. But htey recommend that you bring the level up to 5 after a rain or lots of use in the overnight period to give the pool a chance to return to the 2 level before swimmers reenter the pool the following day. So my question is obviously about what is the chlorine level I should be maintaining? Best Guess has me at 5 and the pool puck bucket says dont swim in water over 2. I dont understand why the requirement for FC rises with higher CYA levels. Do I really need FC of 5 and is that ok to swim in? I am new to all of this and dont want to harm anyone with too much FC in the pool. And what is an ideal level of CYA to strive for? Or is that more of a take what you get kind of thing and you adjust your chlorine accordingly? Thanks for any insights you may have for me. If I continue to use up the pucks before I switch to bleach will I be damaging my water situation with to much CYA? Recommendations? Thanks in advance!

[aylad]

Hello, and welcome!!

Looks like you've been doing your homework and have a pretty good handle on things in your pool. I'm glad that you only added 1/2 the stabilizer that the pool store suggested...most folks keep their CYA levels at 30-50 ppm, so you're not too far on the high side. You are right, though, in the understanding that you DO need to keep higher chlorine levels with higher CYA levels. This page http://poolsolutions.com/gd/best-gue...ine-chart.html can shed some light on the reason why the chlorine levels have to be elevated, along with a link to the chart for reference. As far as the recommended level--well, that's up to you. Most folks find that 30-50 works well for them. But for those in very hot climates, with excessive chlorine consumption that is NOT due to algae or other stuff being oxidized in the water, we recommend that they bump it up a little, maybe to the 50-60 range. I personally keep mine a lot higher than that--80-90 ppm, but my pool seems to be the exception to the norm. My pool is in full sun all day, no shade, hot and humid Louisiana temps, with large kid/dog bather load. If I try to keep my CYA as low as most people, I couldn't afford the chlorine!! With my CYA as high as it is, though, I only have to add one large jug of bleach every other day to maintain my 8-9 ppm of chlorine.

With a CYA of 60, you must keep your chlorine levels between 5-10 ppm at all times. NO lower than 5, or you're asking for an algae bloom and unsanitary water. I know the pool store says no more than 2 ppm chlorine, but that's with 0 CYA, and it's even low for no stabilizer. I don't know how to state it so that it makes sense (the link I gave you above should help you understand it, though), but swimming in a pool with 5-6 ppm of chlorine with CYA at 60, is no different than swimming at a pool with 1-2 ppm chlorine at CYA of zero. With my high CYA and higher chlorine levels, no one ever has any problems--no burning eyes, no faded suits, no other complaints.

If you want to keep using the pucks, you can--but be aware that for every 10 ppm chlorine that gets added, you are also adding 6 ppm of CYA, and you must adjust your chlorine accordingly. You can close the pail of pucks and store them in a dry, cool area, and they will still be good for next year, if you wanted to do that.

One thing I think you should consider is whether or not you plan to close/winterize your pool this year. One of the huge disadvantages to high CYA levels is the amount of ammonia that it can be converted to over the wintertime while the chlorine levels are not being sustained. Some pools experience this, some don't--but in the ones that do, over the winter bacteria converts the CYA to byproducts, including ammonia. This results in opening a pool with 0 CYA but a HUGE chlorine demand, which is hard to overcome but must be overcome in order to get your pool chemistry where it needs to be. This is not a problem for me because my pool stays open all year--but if you plan to winterize your pool, I would not run the CYA up any higher than it has to be. Then again, it's your pool, your choice.

Hope this helps!!

[Watermom]

Hi and welcome to the Pool Forum! Sounds like you have been doing quite a bit of reading here on the forum. Good for you!

You need to keep your chlorine at the levels recommended in the Best Guess chart. If you have a CYA of 60 and run chlorine levels at 2ppm, you WILL end up with algae. I would suggest not using the pucks since they will add more and more stabilizer and you are fine at 60. However, if you choose to go ahead and use up the pucks, you'll have to run higher and higher chlorine levels per the Best Guess chart. (I wouldn't add the rest of the stabilizer.) We typically recommend a CYA level between 40-50 for most pools and you are already a little past that, but still ok at 60. Keep your chlorine levels per the Best Guess table all the time and you will not have any algae problems. Also, it will NOT harm swimmers.

EDIT --- Looks like Jan and I were posting at about the same time, but the advice is pretty much the same.

HA! Beat you this time Jan

[Fishcrazy]

I appreciate the help. I have been using test strips to get some readings when I could not get to the pool store but I have come to think that I need my own test kit to stay on top of this. First off I am not so sure of these test strips and their precision and secondly Im not so sure of the pool store's precision either! Case in point. My strips would not test for CYA and the pool store test result of 60 is not the same as my recently acquired test kit result of CYA = 35. I ran the test twice to make sure that it was right. I look down through the top of the tube at the dot till it totally disappears? Or can you look at the dot through the side of the tube? I read it from the top. Is this black dot test the same one that comes in the kit? Im going to test it again to see if it is correct.

My pool is situated under some shade trees and only gets direct sun around noon for a couple of hours. I do have to keep after the leaves constantly because of this. Every day the skimmer will be full practacly to the point of cloging up the circulation system and then again during the day. I suppose that I will need to cover the pool if I have to leave for any period of time for fear that the leaves will choke off the circulation all together. Any suggestions would be welcome on this problem.

My pool seems to hold its chlorine well. I put a couple of pucks in the other day and the FC level went up to 5 ppm. It seems that when I have added chlorine in the past the level maintains itself for a week. It surprised me to see the FC up to 5 from the two pucks but I guess Im getting to a level of chlorine that is telling me that I need to test more frequently to figure out what level of addition I need to make in chlorine on a regular schedule to maintain the required amount of chlorine. The strange thing about the Best Guess table to me is that there is a higher level of FC required with a higher level of stabilizer. Im sure I dont understand the chemistry but it seems intuitive that if you add stabalizer to make the chlorine more effective then why does more stabalizer cause one to require more FC? I would think that more would require a lesser FC due to the stabilizer effect of protecting the chlorine from being burned off by the sun. Im not thinking about this right, am I?

Im off to check the CYA again and the test strip method for the other readings. Can you recommend a test kit that would complement the one I have or do I just have to end up with 2 CYA tests? Thanks for all the help!

[aylad]

You are right to question the accuracy of the test strips...around here we call them "guess strips" and don't rely on them at all, because they are neither accurate or precise. They are good for telling you if there IS chlorine or if there ISN'T chlorine (sometimes), but don't depend on them for regular maintenance testing.

Sounds like you're doing the CYA test correctly--you view the tube from the top, holding it at waist level, and put the solution (reagent mixed with pool water, shaken VERY well) in until you can't see the black dot. It doesn't surprise me that your test result is different from the pool store--and I would go with yours.

The test kit that we normally recommend is the K-2006, which can be found at the Amazon link in my sig (anything that is purchased through this link results in a small donation to PoolForum, too). If you already have a kit that uses drops to test for pH, TA, CH, and the reagent test for CYA, then you can just add the K-1515 at the same page, which is just the chlorine test that uses powder and a drop system, and is capable of measuring accurately up to 50 ppm, as well as measuring CC.

I'll let the chemists explain why the chlorine levels need to be higher with the CYA being higher, but the bottom line is that as your CYA rises, so must your baseline chlorine. And yes, you do need to test chlorine at least daily to make sure that you're maintaining the required level to keep the pool from going green on you. Remember that the pucks are adding stabilizer, so if you continue to use those, you'll need to test for CYA occasionally, too. Not everyday, but I would say at least weekly or so if you're using the pucks on a regular basis.

Janet

[Fishcrazy]

Just tested water. CYA 35, FC 5, Alk 40, pH 7.2, TH 50.

Alk seems low. Should I do something there and if so what? TH also seems low but what do I need to do for that. These test strip readings are quite different from the pool store readings on 8/5/11. Would readings for Alk go from 120 to 40 and Calcium hardness go from 200 to my TH of 50 in 3 days ? I suppose CH and TH are not the same thing?

The CYA I believe to be correct according to the black dot test. Wonder why their reading was so much higher at 60 3 days ago. Only thing I have done is add 2 pucks chlorine. It did rain 2 to 3 inches since their test but that is the only other input to the pool except the very high heat of 100 deg each day.

[Watermom]

You can add a little baking soda to raise your alk. I'd add a couple pounds at a time slowly to the skimmer while the pump is running. After a couple hours, retest and redose until you get it somewhere between 80-125. Your pH is ok at 7.2 but you don't want it lower. We use 20 Mule Team Borax (laundry aisle at Walmart) to raise pH. You add it in the same way as the baking soda. Actually, you can add them one right after the other. I'd start with a half a box and see what that does for you. You want pH somewhere between 7.2-7.8. I usually keep mine around 7.4-7.6.

If you are going to use the trichlor pucks, you'll need to keep an eye on your pH and your CYA. They are stabilized which means they add CYA. If yours is already at 35, you can use the pucks for awhile, but when your CYA gets to around 50, you'll want to quit using them and only use bleach. You don't want your CYA too high. The trichlor pucks are also quite acidic and will push your pH down.

As far as calcium hardness is concerned, vinyl pools don't need calcium so don't worry about it.

Like Jan said, do yourself a favor and get a good kit. Test your chlorine daily, pH a couple times per week (unless you are tweaking it), alk every couple of weeks (again, unless you are tweaking it), CYA every couple of weeks until you hit 50 and then your CYA should stay pretty stable for the rest of the summer.

Hope this helps!

[CarlD]

OK, I'm going to take my stab at it: I think you should not use the tabs at all. They lower pH, and yours is low, and they raise CYA, and yours is a bit high. Stick with regular unscented bleach. 1 gallon of 6% raises 10,000 gallons of water 6ppm of FC, so figure accordingly. Save them for next year when CYA is low.

With both a low Alk and pH, another alternative is Arm&Hammer Washing Soda, in the yellow box. It will raise both and at $.80/lb, is far cheaper than the pool stores sell it for, though it's the same stuff (sodium carbonate) as their "pH Up!" and similar products.

But baking soda and Borax will work just as well.

Carl

[aylad]

Personally, I wouldn't adjust the levels in the pool based on test strip results. When you spoke about the "newly acquired kit" in your above post, was that just for CYA? Or do you have drop-based testing for evrything else too? If you're depending on the strips, I would not dose the pool based on those results. You'd do better to go with pool store results if they're using drops.

In the post above where I spoke of test kits, if you don't have drop-based testing for TA, CH, pH, Cl, etc...then the K-2006 is the one we recommend. I was under the assumption that the "newly acquired test kit" was drop-based for everything else but chlorine. In that case, then the K-1515 is what you want.

Janet