High combined chlorine

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
Tony Burrows
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Joined: Thu 22 Nov, 2012 05:48
My Pool: 10x25mtr pool

High combined chlorine

Postby Tony Burrows » Mon 26 Nov, 2012 09:49

high combined chlorine ---any way to reduce apart from dilution?


chem geek
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High combined chlorine

Postby chem geek » Mon 26 Nov, 2012 15:43

If the combined chlorine is inorganic chloramines, then you can shock the pool with a higher Free Chlorine (FC) level to get rid of it. If it's organic chloramines, they can persist longer. If you can expose the pool to the UV in sunlight, then that can help considerably.

Your 10x25 meter pool sounds like a commercial/public pool since with 1.5 meter average pool depth that would be close to 100,000 gallons. Is this an indoor or an outdoor pool? If the Cyanuric Acid (CYA) level is too high, then that can slow down chlorine's effectiveness and have Combined Chlorine (CC) increase. For a commercial/public pool with moderate-to-high bather load, you shouldn't need more than around 30 ppm CYA in the pool.
Tony Burrows
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Posts: 2
Joined: Thu 22 Nov, 2012 05:48
My Pool: 10x25mtr pool

High combined chlorine

Postby Tony Burrows » Tue 27 Nov, 2012 07:35

Hi, thanks for that, this is an indoor public pool and holds approx 66,000 gallons of water starts at 3ft =0.9144m shallow end, deepest 6ft=1.829m levels off at 4ft = 1.219m. Cyuranic acid is 2ppm so there is no issues with that, it is something that as never been added to this pool. I think to shock dose is definately worth a go. PH and Free chlorine are absolutely fine it is just the total chlorine which is high so I do not achieve my 3 or sometimes 2 to 1 combined, which I aim for.
thecoypu

High combined chlorine

Postby thecoypu » Wed 28 Nov, 2012 10:48

Hi
I have an infinity pool of 185m3 plus tank of 12m3 , so about 200m3 of water, 20 minutes up a track in remotest Italy and only available to refill from well which certainly does not have that capacity.
Seeing your posts re CYA , I have over the years had more problems with amount of Chlorine and Algeside used, and now testing the CYA , disappearing black spot, which show over 100ppm, could be more. Yes I now know I should not but have used Dichloro for the last few years.
I can refill anything like a sensible % or my neighbours would linch me and water tankers are very impractical plus cost.
Any updates on removing CYA with out replacement of water? Is it worth doing just 10% per few months? and what should I use if not Dichloro, I see mention of Bleach, what household bleach or what ever? what liquid chlorine should I use, any trade names available in Italy.
I also saw a post on CYA being heavier than water and hence undisturbed would tend to settle out to the bottom so removeal from the bottom could be best, is this true, have seen no follow up. :?
chem geek
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High combined chlorine

Postby chem geek » Wed 28 Nov, 2012 11:52

CYA once dissolved does not settle to the bottom. Unfortunately, the only way to remove it is via water dilution/replacement. You could use reverse osmosis (if available), but that's expensive. If you do want to lower the CYA using the least amount of water, then do the water replacement using the sheet method where you remove water from under the sheet while adding new water on top of the sheet which then lowers itself into the pool. The next best approach would be turning off the pump and removing water from one end of the pool while adding it to the other.

If you do continuous dilution or multiple partial dilutions, it will take more water to dilute the CYA. For example, to get a 50% reduction in CYA using continuous dilution, it would take 69% of the pool water volume. Likewise, replacing 100% of the water volume via continuous dilution only does a 63% dilution (so 100 ppm CYA goes down to 37 ppm). Not a problem, but just something to consider.

To avoid CYA buildup, use chlorinating liquid or bleach. If your Calcium Hardness (CH) is low, you could also use Cal-Hypo, but note the following that is independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

In the meantime until you get your CYA lower, you can just maintain a higher FC level to compensate. See the Pool School for more info.
DAVIDLAWSON01

High combined chlorine

Postby DAVIDLAWSON01 » Sat 08 Dec, 2012 08:34

Further to my problems with high chlorine useage and cya, If the only solution is really to change the water , so be it, but what can I do to limit this in the future. What is your opinion of Corona Discharge Ozone generators or other non chlorine systems. If you have knolwedge, how do one work out the size of generator required and can they infact work on a infinity pool with the pump room being totally below pool level.
:?
chem geek
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High combined chlorine

Postby chem geek » Sat 08 Dec, 2012 18:49

To limit this problem in the future, simply don't use only stabilized chlorine (Trichlor or Dichlor). Use primarily chlorinating liquid or bleach or if your Calcium Hardness (CH) is low (say because it's a vinyl pool) you can use some Cal-Hypo. If you don't want to manually dose with chlorine every day or two, then look at getting The Liquidator or a peristaltic pump or using a saltwater chlorine generator.

If you insist on using stabilized chlorine, then using Trichlor will increase the CYA more slowly than Dichlor. To prevent algae growth, you'd need to raise your FC target proportionally to the CYA as it rises, keeping the ratio no lower than 7.5%. If you don't want to do that, then you would need to use an algaecide or phosphate remover to prevent algae growth. An ozone system won't do anything to algae or bacteria that attach to pool surfaces and don't get circulated. Non-chlorine shock doesn't kill algae effectively.

Again, read the Pool School as it has all the information you need. Between the various pool forum websites, there are over 50,000 registered users and over 300,000 unique visitors during the peak month of June so it's not as if properly managing a pool using only chlorinating liquid or bleach is somehow an obscure technique and it's also generally less expensive with no need for algaecides, phosphate removers, clarifiers, flocculants, enzymes, or weekly shocking. Nevertheless, it's a drop in the bucket compared to the 10 million residential pools in the U.S. (though there are no doubt pool owners who use chlorinating liquid or bleach and do not visit these forums).
the coypu1

High combined chlorine

Postby the coypu1 » Mon 22 Jul, 2013 11:44

Hi chem Geek
we did what you suggested last year and managed to replace over half the pool in three sessions with rain and well water over the winter , now it has a green tinge, (algae?) which with high chlorine 56 (dicloro)input and anti algae it does not get any clearer, the ph was7.2 but inspite of putting ph + in does not seem to change on the chart, infact looks a little yellower, so possibly going down, the chlorine this evening is currently at 2 so high but water is cloudy. we re having lots of sun in italy and a lot of pollen blow in from the late massive crop growth, plus stormy weaather.. the chlorine level appears to disapate over night. The water tastes ok and no noticeable smell of chlorine.
any suggestions?
chem geek
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Joined: Thu 21 Jun, 2007 21:27
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High combined chlorine

Postby chem geek » Mon 22 Jul, 2013 15:51

You didn't do what I said. You are using stabilized chlorine, and in your case specifically Dichlor as your chlorine source, but for every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm. Again, read the Pool School and in particular the articles on Defeating Algae and how to SLAM- Shock Level and Maintain your pool.

However, if you have still not purchased a proper test kit, either the TFTestkits TF-100 or the Taylor K-2006 . Otherwise, you are shooting in the dark. Test strips are often VERY inaccurate and pool store testing is often likewise wrong as well.
david123
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Joined: Fri 13 Sep, 2013 18:47
My Pool: I have a client who said she had her pool replastered 2 years back and the beautiful white is now looking blotchy and worn out. I looked and she is right it looks old looking yet it is only two years old. The pool contractor who did the work said this was caused by using too much chlorine. Is that possible... What pool guy uses too much chlorine?
Location: Agoura Hills

Too much High combined chlorine Contractor blames Pool servi

Postby david123 » Fri 13 Sep, 2013 18:57

I am new to the forum so please forgive.... I am a RE Broker who's client's pool's plaster is starting to look old only after two years of being re-plastered. The contractor who preformed the work is blaming the pool maintenance guy for "pouring" chlorine directly into the pool and adding too much... Is this possible and how much Chlorine would do this to a pool? What would be the best way to find out what is happening to the new plaster?

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