Combined Chlorine Won't Break, And Other Issues

[stilloriginal]

Thank you for taking the time to read about my pool problems. I will try to explain clearly the whole picture. I have a pool in central florida that we recently resurfaced and put in a salt system. I was doing the chemicals by taking the water samples to the pool store and following their recommendations. I ended up with stains all over the pool. I called the builder because I was concerned it could be due to the salt system. He called in a professional who took care of everything and now the pool is sparkling clean again. He claimed that it was high chlorine levels which caused the copper in the (brand new) heater to corrode. So I bought a test kit (taylor k-1005 i care) to do the tests myself.

1 month has passed and we have yet to go in the pool, because of consistently high CC levels from day 1. I cannot get it to go down. It is driving me nuts. Every time I test the chlorine, the free chlorine is the right shade, but then I add the drops for the CC reading and it turns dark red. I have tried "superchlorinating" on the salt cell, most recently for 48 hours, and nothing happens, I get the same readings 2 days later.

To confound the issue, when I take the water to the pool store, they read 0 free chlorine, 0 combined chlorine, 0 total chlorine, and tell me to add more. Every time I have ever gone in, they say to add salt (but the salt cell says salt is fine) and add stabalizer, always 2-4 lbs, no matter how many times I add it it always needs more.

It's like banging your head against a wall.

Any help would be greatly appreciated. Thank you in advance.

[chem geek]

Is this an outdoor pool exposed to sunlight? For accurately testing FC and CC, you should use a FAS-DPD chlorine test such as in the Taylor K-2006 kit. You could get the Taylor K-1515 by itself for just the chlorine test, but your test kit doesn't even test for CH or CYA so you really should consider getting the K-2006. Also, as far as high chlorine corroding the copper, did they install the saltwater chlorine generator before the heater instead of after?

[stilloriginal]

Thank you for the quick response!

-yes, the pool is outdoor exposed to sunlight. It in a screen enclosure.

-I think you may possibly be confused about the test kits, or possibly I am. This kit sure does test for CH and CYA. It calls the chlorine test a "DPD" test. I fill the tester to the line, add 5 drops of two different things to get FC, then 5 drops of something else to get TC. (right now adding just 1 drop of the 3rd bottle turns the color red enough to be over 10)

-When we bought the house, the pool had spots on it which we found during inspection. These spots were areas where the plaster was breaking down. The sellers conceded enough to get the pool re-surfaced. We figured to go ahead and also re-tile and put a new heater and salt system at the same time. So, it was all installed on the same day, or possibly the heater was connected like 3 days later, I can't really remember. But all basically the same time.

Thank you so much for taking the time to help. I replaced the filter yesterday because the pressure was going high like every 5 days. Maybe this will be the answer.

edit: I tested the chemicals today again...pH is a little low (I must have added too much acid yesterday, I am sure it will go back up on it's own), FC is 2, TC is infinity, Alkalinity is 100, CYA is 40. (though that last one would depend on your eyesight, my girlfriend saw it dissapear around 70 and she wears really thick glasses. I could still see a very faint outline at 50. )

[waterbear]

Thank you for the quick response!

-yes, the pool is outdoor exposed to sunlight. It in a screen enclosure.

-I think you may possibly be confused about the test kits, or possibly I am. This kit sure does test for CH and CYA. It calls the chlorine test a "DPD" test. I fill the tester to the line, add 5 drops of two different things to get FC, then 5 drops of something else to get TC. (right now adding just 1 drop of the 3rd bottle turns the color red enough to be over 10)

I can assure you that chem geek is NOT confused about test kits. There is a difference between DPD and FAS-DPD testing and FAS-DPD testing is preferred. The reason the pool store was reporting 0 chlorine while you reported high CC is because DPD testing will bieach out and read 0 at high chlorine levels while FAS-DPD testing will acccurately read chlorine levels up to about 50 ppm with an accuracy of up to .2 ppm and is not a color matching test but a titiration (drop counting) test with a color change from pink to colorless that even colorblind people can use. Is your test kit a Taylor or Lestles DPD test kit?

-When we bought the house, the pool had spots on it which we found during inspection. These spots were areas where the plaster was breaking down. The sellers conceded enough to get the pool re-surfaced. We figured to go ahead and also re-tile and put a new heater and salt system at the same time. So, it was all installed on the same day, or possibly the heater was connected like 3 days later, I can't really remember. But all basically the same time.

Thank you so much for taking the time to help. I replaced the filter yesterday because the pressure was going high like every 5 days. Maybe this will be the answer.

edit: I tested the chemicals today again...pH is a little low (I must have added too much acid yesterday, I am sure it will go back up on it's own), FC is 2, TC is infinity, Alkalinity is 100, CYA is 40. (though that last one would depend on your eyesight, my girlfriend saw it dissapear around 70 and she wears really thick glasses. I could still see a very faint outline at 50. )

Is your heater desgined for use in a salt pool? Not all of them are and if it is not then you will continue to have problems. Your heat exchanger should be titanium or a copper/nickel allowy. Also, it is low pH and not high chlorine that usually attacks copper heat exchangers.

If your pool plaster? Is the plaster still curiing (less than a year old?) What brand of SWCG do you have? What is your salt level? While the CYA test is a bit subjective it does not depend on eyesight. The Taylor website has a series of videos and technical writeups that show how to properly do the tests.

[stilloriginal]

Hello water bear,

I am looking for the docs. But this is the heater: http://www.rheem.com...ool-spa-heaters The old heater ran on propane and it was expensive to re-fill. Since we had gas installed when we rennovated the house, we went ahead and installed a gas heater.

-yes the plaster is still curing, it was done in april of this year. I think this is why the pH keeps rising. We used "florida Gem" brand.

-This is the Salt Cell: http://www.pentairpo...elliChlorIG.pdf It is the model IC 40. I don't know the salt level but it reads that the salt level is good. The pool store says I need to add 120 lbs.

-I checked out the taylor videos and realized how to do the diluted test. I am now getting a reading of about 15-20 on the TC. Thanks for that.

Any help is greatly appreciated. I am wondering if I just superchlorinate today with the new filter if It would take care of it.

[LegsOnEarth]

Hello water bear,

I am looking for the docs. But this is the heater: http://www.rheem.com...ool-spa-heaters The old heater ran on propane and it was expensive to re-fill. Since we had gas installed when we rennovated the house, we went ahead and installed a gas heater.

That model of Rheem heater comes standard with a basic copper heat exchanger. It is not designed (or at least ideal) for use in a salt water system as it tends to corrode and lead to the staining issues you were complaining about. You will want to be sure to locate your paperwork and see if you were sold the upgrade for a cupro/nickel exchanger, which is corrosion resistant. I am afraid this is often overlooked by installers though, so my gut says you may have the regular copper.

-yes the plaster is still curing, it was done in april of this year. I think this is why the pH keeps rising. We used "florida Gem" brand.

Both the new plaster and the fact that you are a salt system mean you will see escalating pH. It should begin to slow down as the plaster cures, but you will still see a weekly raise in your pH due to the salt chlorinator.

-This is the Salt Cell: http://www.pentairpo...elliChlorIG.pdf It is the model IC 40. I don't know the salt level but it reads that the salt level is good. The pool store says I need to add 120 lbs.

Do you know what your exact salt level is at? The ideal operational level for an IC40 is 3600ppm. How many gallons is your pool?

You may even want to consider using non-chlorine shock to break out your combined chlorine level, assuming it really is as high as your dillution test is suggesting.

[waterbear]

I would also look for a source of organics in your water creating the CC such as a dead animal in the skimmer or something like that.

[stilloriginal]

I would also look for a source of organics in your water creating the CC such as a dead animal in the skimmer or something like that.

no dead animal, but we do get a ton of spiders every week. I never see them crawling around the patio, only ever in the skimmer or at the bottom of the pool. These guys couldn't be doing it could they?

[waterbear]

Have you checked inside the filter?

[stilloriginal]

yes, I was washing it every 5 days for the last month and finally put a new one in this past weekend. Do you think if I hit "superchlorinate" on the cell for the next 24 hours it would solve it now that I have a new filter?

[waterbear]

You have not told us how many gallons your pool is so I cannot give you dosing but it would be better to shock with liquid pool chlorine (readily available in Florida in refillable carboys) to about 25 ppm AND KEEP IT THERE. until the CC breaks. Also, do not cover the pool if you do use a cover. Does your pool have any autofill by any chance?

[stilloriginal]

Sorry about that. I don't know exactly how many gallons it is. It is 6 feet in the deep end and about 3 in the shallow. A bit too small to be a great lap pool, it looks like a small to medium sized in ground pool. I estimate about 15,000 gallons, maybe a bit more. There is no autofill. only once this summer did I need to re-fill with the hose....we have had so much rain I have had to drain many times... I bet we have gotten close to 20 inches this summer. How do you know if the CC has broken?

[waterbear]

There will be no CC left.

[stilloriginal]

I see....please forgive a noob! any idea why I am showing these levels of CC but the pool store shows 0 chlorine across the board??

[waterbear]

Yes, I said it before. The DPD test they are using is bleaching out because of high chlorine levels. Period.

There is a difference between DPD and FAS-DPD testing and FAS-DPD testing is preferred. The reason the pool store was reporting 0 chlorine while you reported high CC is because DPD testing will bieach out and read 0 at high chlorine levels while FAS-DPD testing will acccurately read chlorine levels up to about 50 ppm with an accuracy of up to .2 ppm and is not a color matching test but a titiration (drop counting) test with a color change from pink to colorless that even colorblind people can use. Is your test kit a Taylor or Lestles DPD test kit?

This is a drawback of DPD testing. What type of test reagents do they use? (Taylor, LaMotte, Palintest, or something else? Liquid, tablet or powder reagents?) Not all DPD tests bleach out at the same level of chlorine but they all do bleach out. This is why we prefer FAS-DPD chlorine testing over DPD testing.

Now if you would like help solving the problem I need some specific info from you:

1 Make and model of the test kit you are using AND A full set of test results with that kit

2 A chlorine test done with OTO (found in inexpensive 2 way chlorine/pH testers--the chlorine color blocks on the tester are shades of yellow). You can pick up n OTO/pH tester at such places as Walmart, Home Depot, some Ace Hardware that have a pool department. Pinch a Penny (found throughout Florida), and just about any other pool supply. When you test with the OTO add 5 drops to the tube and don't worry about matching color. Let it sit for three minutes and then report the color it turned (stayed clear, yellow, deep yellow, orange, brown). OTO only tests total chlorine but is will not bleach out. This will give us an indication of how high the chlorine levels actually are.

3 an answer to this question...Have you ever added any non chlorine shock to the pool, or any algaecdes. If so what are the ingredients?

4 we REALLY need to know how many gallons your pool is. If nothing else we need to know the shape, dimensions and depth. If it is an odd shape we need to break it down into circles, squares, rectangles and triangles that can be measured (with their depths also) so we can calculate the volume of each of the areas and then add them up. Without a good volume measurement for the pool we really don't know how much of anyting to add to change such things as CYA, salt, TA, CH, or even chlorine for shocking.

We can start with these 4 things and take it from there if you want to solve this problem.

Also you need to be testing your own water and NOT rely on the pool store right now. They will only get you deeper into trouble.

[stilloriginal]

waterbear,

thank you again so much for taking the time to help me.

1.The test kit is a Taylor K-1005 icare. Here are the results as of 10 minutes ago (it's been a week since doing the chemicals):

Free Chlorine: 1

Combined Chlorine: 15

pH: 8.5

alkalinity: 90

Calcium Hardness: 550

Cyanuric Acid: 50

2. I got the 3-way kit you recommended. The color in the first few seconds was like mountain dew- and then turned pretty strong yellow. (about a "3"). Here is a pic: http://www.imgur.com/8aaMV

3. The pool was shocked with liquid chlorine from day 1 and then by using the pool's salt system. We have never had an algae problem and never added algecide as far as I know.

4. The pool is not square or round unfortunately it is an amorphous shape. If I take all the curves and "average" them into a square, the pool would be about 25' x 15', 7 feet deep and the deep end and 3.5 at the shallow, with the dropoff about in the middle.

There is an attached spa which is 6' in diameter, with a 3' diameter "foot area", each step about 1.5' deep.

So, I calculate the pool is 1969 cubic feet, but since the bottom edges are all curved, and there are stairs, I would take about 10% off of this and just call it 1770 cubic feet. I calculate the spa is another 40 cubic feet. 1810 cubic feet should equal 13,500 gallons. Please let me know if you see the math any differently.

The water here in florida is high in calcium deposits so I don't know if draining and re-filling will sove that "issue". we are planning to invest in a water softener and at that point may consider re-filling the pool with filtered water.

Thank you again for all of your help!!!!

[waterbear]

waterbear,

thank you again so much for taking the time to help me.

1.The test kit is a Taylor K-1005 icare. Here are the results as of 10 minutes ago (it's been a week since doing the chemicals):

Free Chlorine: 1

Combined Chlorine: 15

pH: 8.5 If the pH is truely this high and it is not a result of a very high chlorine level this is a major problem. You want to use muriatic acid and NOT dry acid with a SWCG to lower pH and TA, btw.

alkalinity: 90 This should really be a bit lower for a salt pool, 70 ppm is a good place. Higher TA means faster pH rise.

Calcium Hardness: 550 This is another reason to lower the TA. Since the calcium hardness is high a lower TA wil definately help avoid scaling conditions if the pH should spike.

Cyanuric Acid: 50 This is the MINIMUM recommended level by Pentair. It is better to run a salt system at the MAX recommended level of CYA. IT indirectly leads to better pH staibility. The explanation is somewhat complicated but you would be better off with the CYA at 80 ppm and yo would then want to maintain the FC at 5% of that as a minimum level or 4 ppm and try to keep the FC between 4-5 ppm at all times.

My suggestion is to get the Taylor FAS-DPD test kit K-1515 which is only the FAS-DPD chloirne test. It is much better than the DPD test in your kit. There is a problem with your testing for some reason and as you read on you will understand. Your iCare kit will then be almost the same as the K-2006 test kit we recommend except that your pH test is not as precise but it is serviceable. There seems to be a problem with your DPD testing.

2. I got the 3-way kit you recommended. The color in the first few seconds was like mountain dew- and then turned pretty strong yellow. (about a "3"). Here is a pic: http://www.imgur.com/8aaMV

The OTO test is "bulletproof" and will not bleach out and tests only total chlorine (free chlorine + combined chlorine) so if you had a test result of about 3 ppm when the test sat for 3 minutes it means that the combined chlorine cannot be 15 ppm! Something is wrong. Perhaps the reagents you have in the iCare are bad. My suspcison would be the R-0003. The fact that you said the OTO test looked like mountain dew initially is strange. Do you mean yellow green? IF the CC was truly 15 ppm then the color would have been a deep yellow bordering on orange and wold have looked almost brown as the drops were added and before they were mixed.

3. The pool was shocked with liquid chlorine from day 1 and then by using the pool's salt system. We have never had an algae problem and never added algecide as far as I know.

4. The pool is not square or round unfortunately it is an amorphous shape. If I take all the curves and "average" them into a square, the pool would be about 25' x 15', 7 feet deep and the deep end and 3.5 at the shallow, with the dropoff about in the middle.

There is an attached spa which is 6' in diameter, with a 3' diameter "foot area", each step about 1.5' deep.

So, I calculate the pool is 1969 cubic feet, but since the bottom edges are all curved, and there are stairs, I would take about 10% off of this and just call it 1770 cubic feet. I calculate the spa is another 40 cubic feet. 1810 cubic feet should equal 13,500 gallons. Please let me know if you see the math any differently.

Nope. If you have about 1810 cubic feet then that should be about 13.5K gal. It's a starting point for dosing chems and we can tell if we need to adjust up or down if we dose a chem that should give us a specific change and it is either high or low.

The water here in florida is high in calcium deposits so I don't know if draining and re-filling will sove that "issue". we are planning to invest in a water softener and at that point may consider re-filling the pool with filtered water.

I live in Fl also and know the water well. It is not uncommon for the CH to be 600 ppm or even higher in some parts of the state. I have seen that where I live myself Be aware that a water softener will not have the capacity to fill your entire pool but if you start topping off with soft water it will help, as will a partial drain..

Thank you again for all of your help!!!!

There is something wrong with your test results somewhere. I am inclined to believe the results of the OTO test over the DPD test since high combined chlorine would be indicated by a very dark yellow color with the OTO test. How many drops of OTO reagent are you adding to the sample?

Right now I am puzzled since I suspected that your DPD test was bleaching out but now I think the pool store might be more on the mark and that your chlorine was actually 0 ppm or close to it. How is the pool store testing (liquid reagents, dry reagents in vials or tablets, strips with or without a strip reading machine?)

I would still strongly suggest getting the Taylor FAS-DPD stand alone test kit to supplement your iCare and testing with a 10 ml sample size (.5 ppm drop equivalent) to see what you get for FC and CC. I suspect the results will be very different than what you are getting right now!.

[stilloriginal]

waterbear,

Take a look at this video on the Taylor site: http://www.taylortechnologies.com/products_choose_slideshow.asp?KitNumber=K-1005

Click on "To Test Chlorine with Liquid DPD [updated 3/5/10]"

That is the Taylor test that is showing high amounts of combined chlorine. If you watch the example video....THEY GET THE SAME RESULTS AS ME. At this point I think Taylor is selling a bunk kit, and I am thinking about calling and complaining. This seems to have been a heck of a lot of work all for nothing. Thanks for your help.

[waterbear]

If the video is the same results you are getting then your CC is only 2 ppm! The example they show is 3 ppm FC and 5 ppm total chlorine and that would leave 2 ppm of combined chlorine. If your readings are off scale then you would need to get a kit that can test a higher range (2000 series DPD with dilutions or FAS-DPD) or dilute your sample with distilled water, test the diluted sample, and multiply the test results by the dilution factor.

If you dilute 1 part pool water with 1 part distilled water multiply the test results by 2

If you dilute 1 part pool water with 2 parts distilled water multiply the test results by 3

If you dilute 1 part pool water with 3 parts distilled water multiply the test results by 4

If you dilute 1 part pool water with 4 parts distilled water multiply the test results by 5

Realize that the higher you dilute the more accuracy you lose.

The K-2005 has diluton marks for 1:1 and 1:4 dilutions molded on the comparator. The K-2006 is a titration test that directly reads FC and CC up to about 50 ppm (in actual practice) with a precision of either .2 or .5 ppm which is why it is the test we prefer.

The iCare kit is not a bogus kit and, except for the chlorine and pH tests, is exactly the same as the K-2005/K-2006. However, it IS possible that you have a bad reagent (they do have a shelf life and you don't know how long the kit was sitting on a shelf or in a warehouse before you bought it) or your comparator is not clean when you start

One thing that many people don't realize is that many men have difficulty in differentiating the shades of red that the DPD test uses (women are much better at it). This is another reason that the FAS-DPD kt is preferred. This difficulty is not color blindness since, with practice, many men who have this trouble can learn to overcome it. It is because the "red color vision gene" is on the X chromosome and men have one X while women have two.

Finally, other oxidizers can show up as combined chlorine such as potassium monopersulfate (non chlorine shock), ozone, and bromne (found in many algaecides). Have you ever used a non chlorine shock or a special shock for salt pools? (many of them are or contain MPS)

[stilloriginal]

waterbear,

in the video, when the add the 3rd reagent (starting at 1;10), it appears to turn a very strong hue to me, much stronger than the "5" on the comparator. This is the same hue as my water turns. (here is a pic: http://www.imgur.com/NIOr2 ) I end up having to do a 1/4 dilution and get a final reading 15-20. Or am I missing something???

[waterbear]

In the video the sample is 3 ppm for fc and 5 ppm for TC making CC 2 ppm and it looks like that to me also whien I view the vid.

In your picture it is hard to tell since the comparator should be help up against a blue sky or a daylight light box. However the OTO test does look to be about 5 ppm TC from the color. since it is not at an angle so I am able to see through it better. The DPD TC reading is certainly no more than about 6 or 7 from the color I think I am seeing but it is hard to really tell from your picture. At any rate the two tests (OTO and DPD) are close in the picture (and they are never exactly the same for TC anyway). I am beginning to think that you are not able to differentiate shades of red, and seeing a lot more CC than actually exists. which is more the reason to get the FAS-DPD chlorine test that both chem geek and I mentioned above. It is a drop counting test with a definite color change from pink to colorless for both the FC and CC and directly tests CC. Even someone with colorblindness can use this test and get accurate results. This is why we recommend the Taylor K-2006 over their other test kits even though it costs a bit more. It is easiest to use and there is no guessing as to which shade you are matching on the comparator.

[waterbear]

I just though of something else...do you by any chance have an ozone generator in your pool?