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Thread: chlorine and chlorine-free shock

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    chlorine and chlorine-free shock

    is there any benefit to using both chlorine and chlorine-free shock at the same time?

    is it bad to use them both at the same time?

    this forum is great. glad i found it.

    thanks!

  2. Back To Top    #2
    frustratedpoolmom's Avatar
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    Re: chlorine and chlorine-free shock

    Can you post test results, so we have an idea of your levels?

    Non-chlorine shock is better for indoor pools and spas - not really suited for outdoor pools.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Re: chlorine and chlorine-free shock

    i am just asking in general. i have done this in the past and was wondering about if i may be doing a chemical no no.

    thanks.

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    frustratedpoolmom's Avatar
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    Re: chlorine and chlorine-free shock

    Not really, certain non-chlorine shock products can do funny things to the FC and CC levels. No reason to use nonchlorine shock really. It's expensive and doesn't really have a benefit in an outdoor pool.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: chlorine and chlorine-free shock

    interesting that you say that non-chlorine shock is not for outdoor pools. i never heard that.

    i believe non-chlorine shock has its place. it is not a disinfectant like chlorine, but oxidizes left over or suspended waste in the pool. it can really clear up things and let the chlorine do its work. this is true for indoor and outdoor pools. if you keep your chlorine levels where they should be at 2-4ppm, you can use non-chlorine shock to clean/clear the pool of the left overs on a weekly basis. if you have maintained the proper chlorine levels of 2-4ppm, you really don't need to superchlorinate with chlorine shock. why wait 24 plus hours for the chlorine boost/shock to wear off? use non-chlorine oxidizing shock and swim in an hour.

    my original question is mainly a chemical question and not about the validity of using non-chlorine shock.

    i want to know if chemically they should not be used together at the same time.

    thanks for the responses.

  6. Back To Top    #6
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    Re: chlorine and chlorine-free shock

    The two work differently. If you understand how they work you will understand when and how to use them. First of all you need to understand that shocking is something that a well maintained outdoor pool rarely needs. Indoor pools, since they are not exposed to sunlight, do benefit from shocking.
    Non chlorine shock works by oxidizing organics before they can combine with the chlorine and form chloramines. The biggest problem with using non chlorine shock, besides the fact it lowers pH and 'eats up' TA much like trichlor (and adds sulfates to the water) is that it will test as combined chlorine unless special reagents are used so it does make water testing problematic. Non chlorine shock is not that effective at destroying CC that is already present in the water.
    It is best used as a maintenance product on a regular schedule. As I said, this is more useful in indoor pools that are not exposed to sunlight. It is not a necessary expense in outdoor pools where it is much easer to break down chloramines by a combination of shocking and sunlight.

    Also, where do you get the idea that chlorine levels should be kept at 2-4 ppm? Chlorine levels needs to be kept at the proper level for the CYA in the pool.

    Perhaps if you clicked on the pool school link in the upper right of every page and read everything in it you would have a better idea on the various aspects of pool chemistry and chemicals. It couldn't hurt!

  7. Back To Top    #7

    Re: chlorine and chlorine-free shock

    thanks for the reply.

    where did i find 2-4ppm free? aah, how about checking your local commercial / public pool code? if it is good enough for the the gov, it is good enough for me. i know here in illinois it is 1-4ppm free chlorine residual. should i discount that the government does not know what they are talking about?

    also, i looked at the pool school. did you see this? "Acknowledgment: The original Chlorine/CYA "Best Guess" chart was developed by Ben Powell. Richard Falk (chem geek) has refined and expanded on that original to produce the Chlorine/CYA Chart by Chem Geek based on experiences with members on this forum and the old Pool Forum and conformation to chemical theory."

    theory. great. i don't mean to offend, but i am going to go with my state codes and nspf.org recommendations.

    it is great people are here on this forum to help, but lets not take everything that people write as gospel.

    that includes what i write.

  8. Back To Top    #8

    Re: chlorine and chlorine-free shock

    Not theory. Hundreds if not thousands of people on this site use these numbers every day, and personally, I would trust just about anyone here faster than the government. You know, they don't ALWAYS have your best interest in mind...

    Let us know when you have a problem, and we will be glad to help you out!

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by chitown
    thanks for the reply.

    where did i find 2-4ppm free? aah, how about checking your local commercial / public pool code? if it is good enough for the the gov, it is good enough for me. i know here in illinois it is 1-4ppm free chlorine residual. should i discount that the government does not know what they are talking about?

    also, i looked at the pool school. did you see this? "Acknowledgment: The original Chlorine/CYA "Best Guess" chart was developed by Ben Powell. Richard Falk (chem geek) has refined and expanded on that original to produce the Chlorine/CYA Chart by Chem Geek based on experiences with members on this forum and the old Pool Forum and conformation to chemical theory."

    theory. great. i don't mean to offend, but i am going to go with my state codes and nspf.org recommendations.

    it is great people are here on this forum to help, but lets not take everything that people write as gospel.

    that includes what i write.
    What you fail to realize is that there is a LOT of practical experiece backing up what we have on the forum and as far as state codes go, here in FL for commercial pools the pool is considered swimmable with up to 10 ppm FC so there is not even a lot of agreement from state to state. Several states cap FC levels at 5 ppm. Each individual health department sets their own standards, often based on flawed studes that were funded by some of the major trichlor manufacturers (such as the infamous st. petersberg study.)

    NSPS is simply ONE of the organizations that certify pool inspectors and CPOs and are by no means the final authotiry.
    In fact ANSI standards are actually set by APSP and it is intersting that the NSPS and APSP standards for pools and spas do not agree with each other on all parameters.
    The AFO couse offered by the National Recreation and Park Association is also a major certifier of commercial water facility operators. So you see, do not take any of these organizaton's info as the gospel.

    As far as the info on many governemt pool info sites, including the CDC. much of it is out of date and inacurate. Case in point this factsheet from the CDC http://nspf.org/Documents/cdcarticles/cdcfnlphcl.pdf
    While the info in it is correct for a pool with NO CYA in the water the effects of pH on chlorine's effectiveness go out the window with even small amounts of CYA present and pH actually has little impact.

    As far as commercial pools go I actually have experience caring for them so I know a bit about the subject that goes way beyond theory!

    You posted another question in this forum that was based on bad information 'from the industry' about draining from the bottom to lower CYA. I hope that you can see that the 'authorities' out there often do not know what they are talking about. This same misinformation I have actually heard being taught in NSPS CPO courses and I have also heard in the same courses that the CYA is all on top of the water! Conflicting info that does not go along with the basic chemistyr of ionic solutions! That does not put a lot of faith in CPOs trained by NSPS as being any kind of 'expert' for me!

  10. Back To Top    #10

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    Re: chlorine and chlorine-free shock

    The EPA sets a limit of 4 ppm FC because that is the limit set for drinking water. Does that make sense? You aren't drinking 6-8 quarts of chlorinated pool water every day and skin absorption is not anywhere near that high (97% of the FC is bound to CYA and CYA skin absorption is minimal as described here). Also, the EPA does not understand the chemistry of chlorine and CYA. They were not aware of the chemical equilibrium determined in 1974 as described in this paper (I know because I've talked to the relevant people in that division that approve disinfection products including those for pool use). I suggest you read at least the introductory section of that paper.

    As for state codes and the APSP (formerly NSPI) and NSPF CPO guidelines, you need to understand that much of this is driven by the chlorinated cyanurate industry that claims that "real pools" don't follow the chemistry yet we've got thousands of pools at both The Pool Forum and here at Trouble Free Pool that follow the chlorine/CYA relationship as predicted, when conditions are otherwise conducive to alage growth (i.e. there are nutrients and no algaecides). We don't have a financial incentive to claim that Cyanuric Acid (CYA) levels don't matter, but these corporations that profit from chlorinated cyanurate products (e.g. Trichlor, Dichlor) do.

    I and others who are technically oriented on this forum have pored through the scientific literature and found that the chlorine/CYA relationship holds extremely well in almost every case, be it killing of bacteria (here, here, here, here), inactivation of viruses (here), protozoan oocysts (here, here), inhibition of algae growth (this paper claimed no correlation, but real pools say otherwise; Sommerfeld never wrote back to me when I questioned this), and oxidation of ammonia and organics (here) as well as correlation with ORP (see this post). I've also gone through field study data where the industry makes claims that only Free Chlorine (FC) matters yet I saw that bacteria are killed so easily that you can't even draw that conclusion from such studies and that hypochlorous acid (HOCl) is at least as good a predictor though they never looked at that correlation nor the FC/CYA ratio as a proxy (see this thread).

    You can follow the research and the science for yourself or have someone you know who can follow the chemistry and microbiology tell you for themselves. This isn't anything I or anyone else is making up.

    Also, there are chemical facts that aren't taught in NSPF CPO nor APSP TECH courses nor found in books or in government literature or state codes or anywhere else, yet they are absolutely indisputable and based on the most fundamentals of chemistry:

    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.
    For every 10 ppm FC added by ANY source of chlorine (and accounting for chlorine usage/consumption), the salt level increases by at least 8 ppm.
    For every 10 ppm FC added by chlorinating liquid or bleach (sodium hypochlorite) or lithium hypochlorite, the salt level increases by an additional 8 ppm (so 16 ppm total).

    Simple math shows that even a pool with a low 1 ppm FC per day usage using Trichlor would have CYA increase by over 100 ppm in 6 months if there were no dilution of the water. Nobody teaches this, and this is what happened in my own pool years ago that got me interested in pool water chemistry when I got no help from pool stores (my CYA went from 30 to 150 after 11 months of pool use over 1-1/2 seasons and the water got dull and chlorine demand went way up from previously being around 0.7-0.8 ppm per day -- the pool is covered most of the time, has an oversized cartridge filter, and minimal splash-out and I was even using PolyQuat algaecide, but only every other week).

    I have tried to get NSPF to add the above info to the CPO course, but they haven't done it; I have asked manufacturers to add it to their labels or supplemental materials, but they won't do it (they say are bound by EPA FIFRA rules which are a long and expensive process, but the above are facts not relating to dosing or disinfection claims so can be approved in a quick 30-day process as easily as a company address change). With my experiences, I would not simply trust what a government agency nor industry trade group nor corporation says without verification. And yes, you are right not to simply trust what anyone, including myself, writes on the Internet. That's why I always try to document my sources, try to use peer-reviewed scientific research whenever possible, and give details of any calculations or logic that I use so you can determine the veracity of what is being written. Most of these details are kept in The Deep End since they are mostly technical, boring, and not of general interest to most pool owners who simply want to know what to do, not why it works.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: chlorine and chlorine-free shock

    I told my wife there were some very smart people here on the forum and now you all go and prove it. Thanks for the interesting discussion.
    18,000 Gallon IG, Gunite, Cartridge filters
    Rainbow 320 Chlorine feeder (not in use anymore), 2.0HP Pentair WhisperFlo
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by waterbear
    The two work differently. If you understand how they work you will understand when and how to use them. First of all you need to understand that shocking is something that a well maintained outdoor pool rarely needs. Indoor pools, since they are not exposed to sunlight, do benefit from shocking.
    Non chlorine shock works by oxidizing organics before they can combine with the chlorine and form chloramines. The biggest problem with using non chlorine shock, besides the fact it lowers pH and 'eats up' TA much like trichlor (and adds sulfates to the water) is that it will test as combined chlorine unless special reagents are used so it does make water testing problematic. Non chlorine shock is not that effective at destroying CC that is already present in the water.
    It is best used as a maintenance product on a regular schedule. As I said, this is more useful in indoor pools that are not exposed to sunlight. It is not a necessary expense in outdoor pools where it is much easer to break down chloramines by a combination of shocking and sunlight.

    Also, where do you get the idea that chlorine levels should be kept at 2-4 ppm? Chlorine levels needs to be kept at the proper level for the CYA in the pool.
    This is interesting to me. If MPS is effective in preventing chloramine development and not that effective eliminating cc already present, what's the chemical benefit 'after the fact' in using it? Also, enzymes also oxidizes waste that clouds water, and also has no effectve on cc's - so why use non-chlorine shock at all once chloramines are formed?
    Barry
    PS - I don't take everything written here as gospel but rather as additional information to help me understand all the dynamics and interactions between factors so I can make a better informed decision when treating my spa....not to mention the good feeling knowing you're in control. Thanks
    Sundance Hot Tub 365 gal, acrylic
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by chitown
    if you keep your chlorine levels where they should be at 2-4ppm,
    If you are keeping your cl level at 2-4ppm & you have so much cya that you need a partial drain as referenced in this thread post112455.html#p112455 your cl level is to low.

    A cya level of 50 the minimum free cl level is 4ppm
    I consider myself very lucky I found this site before the pool store found me-pool owner since Nov 2008- Stunningly clear 17,000 gal fiberglass pool, thanks to this site, installed in 1982-24" 3.1sq. ft sta-rite sand filter, 1 hp - 2 speed wisperflo pump-WFDS-4

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    frustratedpoolmom's Avatar
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by BC
    If MPS is effective in preventing chloramine development and not that effective eliminating cc already present, what's the chemical benefit 'after the fact' in using it? Also, enzymes also oxidizes waste that clouds water, and also has no effectve on cc's - so why use non-chlorine shock at all once chloramines are formed?
    Barry
    Exactly.

    I have shocked my pool 5 times in over 2 years, 3 times before leaving on extended vacations and twice before winterization. Routine shocking of a pool is not necessary if you maintain proper FC levels (mine are 3-7, btw.)

    Edited to remove political comments. JasonLion
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by BC
    If MPS is effective in preventing chloramine development and not that effective eliminating cc already present, what's the chemical benefit 'after the fact' in using it? Also, enzymes also oxidizes waste that clouds water, and also has no effectve on cc's - so why use non-chlorine shock at all once chloramines are formed?
    MPS is a selective oxidizer so it is better at oxidizing some organics than chlorine, but generally speaking it tends to attack some of the same nitrogenous chemicals that chlorine either combines with or fully oxidizes so it's better as a preventative of chloramine formation. Even with chlorine combining with ammonia, chlorine alone will continue to oxidize it -- it just takes a little longer (hours, when CYA is present) and can produce disinfection by-products such as nitrogen trichloride (but in very low amounts, when CYA is present). The largest component of sweat and urine is urea (see Table 4.1 in this WHO document) and that takes a lot longer to oxidize from chlorine (days) without the help of UV from sunlight or high temperatures (as in a spa). This is one reason why MPS can be more helpful in indoor pools, though reported results have been mixed.

    Enzymes are not oxidizers themselves, but chemical helpers that accelerate specific existing chemical reactions (by lowering the activation energy) so can accelerate the oxidation of organics by chlorine (or dissolved oxygen). They usually aren't necessary as chlorine does a pretty decent job on its own. Bather waste from sweat and urine does not usually cloud water. Cloudy water from swimmers more typically comes from suntan lotions and other additives put onto the skin. Some of these products don't oxidize well and can form a film on the water or scum on tile. Usually these can be taken care of by scum balls or can get caught in the filter. In my own experience with a wife who swims in our pool every day and uses lots of suntan lotion, the film will breakdown with chlorine, but it takes a bit longer (a day or two) so the choice I have is to use extra chemicals to get rid of it faster or just to live with it as a minor annoyance (I do the latter). It does tend to dissipate from disturbing the water surface (breaks it up) and sunlight (may help to oxidize it faster, though that's speculation on my part) so keeping our pool covered probably exacerbates this minor issue.

    Richard
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    frustratedpoolmom's Avatar
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    Re: chlorine and chlorine-free shock

    Edited to remove political comments. JasonLion [/quote]

    AAWEEEE.....
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by frustratedpoolmom
    Edited to remove political comments. JasonLion
    AAWEEEE..... [/quote]

    oooooooooooooo Yours must have been much worse than mine, Frustrated!
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by frustratedpoolmom
    Edited to remove political comments. JasonLion

    AAWEEEE.....
    Hmmm, FPM and chitown are both from Illinois and political comments have been removed. Now, what in the world political EVER happens in Illinois? Has anything at all even remotely political happened in Illinois in, say, the past year or so? I'm really clueless here!

    We now return to your regularly scheduled thread after this hijack!

  19. Back To Top    #19
    frustratedpoolmom's Avatar
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    Re: chlorine and chlorine-free shock

    524 federal corruption convictions between 1997-2006. I'd say we've had our share of troubles for more than the last year!!!
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
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    Re: chlorine and chlorine-free shock

    Quote Originally Posted by Wes45
    I told my wife there were some very smart people here on the forum and now you all go and prove it. Thanks for the interesting discussion.
    Some of us are more like idiot savants! We know our pools but can't find our own foot to tie our shoes!

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