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  1. R

    Floc and sand

    "Slow- rate " is faster than 0.1-0.4 meters/hour. You probably meant to say 1 - 4 meters/hour , and even this speed is very very slow. Drinking Water Plants run their Filters at about 7 meters/hour. "High-rate" is up to 20 GPM, which means not 12 meters/hour but 48.80 meters/hour. I also...
  2. R

    CO2 as a pH reducer - Problems with TA

    Thanks Jason - I knew there was a non-linear effect. Still - I think that by keeping a constant pH of 7.30 and a TA of 70 the consumption of CO2 should not be more as if I would keep the pH at 7.5 and the TA at 70. Naturally one would need a bit more quantities of CO2 at the beginning to...
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    CO2 as a pH reducer - Problems with TA

    Yeps - very serious. You just made me go back into my basement to look for those hand written notes from a public pool about 20 years ago. . . lol Bather load as well as Sodium Hypochlorite consumption was daily documented by the technical staff from this particular indoor swimming pool. Back...
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    CO2 as a pH reducer - Problems with TA

    I do remember coming across a study ( which I can't find anymore) which showed into more details the consumption rate in regards to the time being spent in the pool. Possible it was a bit longer than those 3 min. I stated. I find the chlorine demand you stated ( 4 grams / person) very low...
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    CO2 as a pH reducer - Problems with TA

    The majority of chlorine consumption per person happens right after the swimmer goes into the pool. If they stay 45 min it is only slightly higher than if they stay just 3 min. in the pool. (unless it is a competitive swimmer who sweats a lot and does heavy physical exercise in the pool ). As...
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    CO2 as a pH reducer - Problems with TA

    James - There are actually 2 Pools in this building. I described the bigger one ( 450.000 gal) , but the "Kiddie" Pool ( 65.000 gal) has more or less the same readings than the big pool. Turnover time on the big pool = once every 3 hours ( 8 times in 24 hours ) small...
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    CO2 as a pH reducer - Problems with TA

    IMHO a pH of 7.8 is way too high. 7.3 is good - if it's up to me I'd bring it down even lower ( 7- 7.2) but the municipality which owns the pool is afraid to to so, due to misinformation ( partly again by the pool builder). By running the pH at 7.8 the Hypochlourous Acid is probably only 1/2...
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    CO2 as a pH reducer - Problems with TA

    Thanks Jason and Chem Geek for your input. I also think the easiest and least expensive method would have been to simply use a liquid based pH reducer (e.g. muriatic acid 35 %). As we all know, there are always some political reasons and justifications involved when a municipality decides...
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    CO2 as a pH reducer - Problems with TA

    I came across a public indoor Pool ,which is using CO2 in order to bring down the pH. Sodium Hypochlorite is used as a disinfectant. Now : It seems the TA creeps up by using CO2 and more and more CO2 is used the higher the TA gets. . . Doesn't really make sense to me that CO2 brings up TA - I...
  10. R

    Interesting Study (Dissertation) on DBP's in indoor pools

    Re: Interesting Study (Dissertation) on DBP's in indoor pool Typically. Take a look at the members of the so called "advisory committee"and "Board of Directors" of NSPF. I do suspect it is not in their commercial interest to "lower down " suggested FAC levels in public pools. Basically the...
  11. R

    Interesting Study (Dissertation) on DBP's in indoor pools

    Re: Interesting Study (Dissertation) on DBP's in indoor pool There is probably nothing to panic about when you swim in an outdoor Pool - I do agree with you. Problematic is in the indoor pools and especially for the people who spend lots of time in the enclosed Pool environment. Basically...
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    Interesting Study (Dissertation) on DBP's in indoor pools

    Re: Interesting Study (Dissertation) on DBP's in indoor pool The risk of exposure to THM's in pool water is about 93 times ( ninety three) higher than exposure by tab water ingestion ! ( B.Levesque and Agazotti study) In other words - you could drink tab water up to 80 ppb of THM and the...
  13. R

    Interesting Study (Dissertation) on DBP's in indoor pools

    Re: Interesting Study (Dissertation) on DBP's in indoor pool Don't know what he got wrong there :?: If using sodium or calcium hypochlorites it raises the pH , therefore it must be lowered by (for example) Hydrochloric Acid ,and if using chlorine gas (to put it in simple words), we need to...
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    Interesting Study (Dissertation) on DBP's in indoor pools

    To my knowledge this is the first extensive study which examined indoor pools in the USA . It seems that finally attention is being paid on DBP's in order to protect public health. For good reason the German regulation (DIN 19643) limits the amount of THM's at max. 20 microgram/l. More and more...
  15. R

    Ideal ORP readings

    Richard, You posted ( at 4:06 pm )- I edited at the same time, so I guess you did not read what I added to my posting: Here it is what I added -> (from the World Health Organisation) -> 5.12.4 Oxidation–reduction potential Continuous control of the oxidation–reduction potential (ORP) is...
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    Ideal ORP readings

    You forgot to post the next sentence after the one you quoted : In short, it cannot be claimed that a high redox potential could function as an absolutely sure yardstick of the disinfecting power of swimming-pool water. But according to the results of this investigation, the error is less than...
  17. R

    Ideal ORP readings

    Richard, I agree what you are saying. What I am trying to say is that ORP's is a useful parameter in order to see how efficient the water treatment is. If I see a ( public pool) which has 650mV (assuming that the ORP probe is calibrated and really gives me the correct reading) with a pH of 7.2...
  18. R

    Ideal ORP readings

    I suppose since he worked for a company which manufactures ORP controllers his article is not accurate then. . . Mmhh. . . OK - what about this research -> http://www.ncbi.nlm.nih.gov/pmc/article ... 6-0108.pdf . . . or this. . . (from the World Health Organisation) -> 5.12.4...
  19. R

    Ideal ORP readings

    Re: ORP readings vs. Free Chlorine readings I know quite a few studies which are written in German and French about the importance of high ORP's. Also found something you may or may not find interesting - IMHO this article summes it up quite nicely -> http://ppoa.org/?p=572
  20. R

    Sodium Bicarbonate / TA - pH Hydrochloric Acid /TDS

    I should have mentioned that this pool is not a SWG pool. So - if I want to have a pH of 7.2 and a TA of 100 - how does one proceed in getting those numbers ?
  21. R

    Sodium Bicarbonate / TA - pH Hydrochloric Acid /TDS

    They are also adding sodium bicarbonate even if their pH is higher - as long as they bring up the TA ( remember. . . their chemical supplier told them that's the way to do it. . .lol) Now - when you refer to carbonate alkalinity shouldn't there be a minimum of about 30 ppm (in CaCo3)? Doesn't...
  22. R

    Does sand becomes less effective over time

    Silica sand is quite resistant and should last about 10 years easily ( no matter what your pool supply store tells you) Attention should be paid that there is not too much sand in the filters in order to allow a proper lifting of the sand in the filter when performing a back wash.
  23. R

    Sodium Bicarbonate / TA - pH Hydrochloric Acid /TDS

    I need some opinion / advice from the experts here. . . (chem geek - I hope you are reading this) OK - I went to see a public indoor pool today ( 250.000 gal) in order to take a look at their filtration system. Filters are old, rusty and they are thinking of replacing them. Crystal clear...
  24. R

    Ideal ORP readings

    Exactly. That's one of the reasons I am an advocate of promoting low FC levels . Thanks for the link posted above.
  25. R

    Certified Pool Operator (CPO) training -- What is not taught

    Re: Certified Pool Operator (CPO) training -- What is not ta I could argue in saying "what makes you think your test kit for measuring FC is the right one ?" You might be using a Lamotte or a Taylor or whatever. . . How do you know if "yours" gives you the right reading ?
  26. R

    Certified Pool Operator (CPO) training -- What is not taught

    Re: Certified Pool Operator (CPO) training -- What is not ta Not necessarily. The "kill Time" depends -of course - also of the pH. And that's exactly my point. It's all about the ORP's. I can have 2 ppm and a pH of 8.2 or 1 ppm with a pH of 7. In which example I got a faster killing time...
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    Certified Pool Operator (CPO) training -- What is not taught

    Re: Certified Pool Operator (CPO) training -- What is not ta For the following reasons: in order to see/verify if I get proper disinfection. Again - the ORP is a "helping parameter" . I can reasonably assume that by having more than 700 mV there should not be any issues in terms of...
  28. R

    Certified Pool Operator (CPO) training -- What is not taught

    Re: Certified Pool Operator (CPO) training -- What is not ta I did read the links and also searched in my documents about this subject. From what I have seen in public pools I would not be surprised that those different readings what people get also has to do with the fact that lots of pool...
  29. R

    Ideal ORP readings

    I guess this might be one of the reason CYA is not allowed for public indoor pools.
  30. R

    Ideal ORP readings

    As I was saying before : The aim is to run with as low as possible chlorine levels by still obtaining high ORP's for the exact reason you just wrote above.