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Thread: Why is basic water chemistry so controversial?

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    Angry Why is basic water chemistry so controversial?

    I just had a run-in with a pool repair guy. Unfortunately I can't fire him because he's working on behalf of my insurance company. When he told me that he was taking my pool filter offline for a couple of days I asked him if he could run a bypass so I could circulate the water. He told me he didn't want to because it would be a lot of work and I shouldn't have any problems with algae. Then he asked me how my "stabilizer" was, and I told him it was 40 ppm. "That's WAY too low!" he exclaimed. He went on: "This is Southern California. You need at least 80 or 100." When I explained that I don't want it that high, he gets all exasperated and asks why. I explain that I don't want to have to add 7 gallons of bleach just to SLAM my pool. Then he tells me that "chlorine lock is a myth" and that you don't need more chlorine with higher stabilizer levels. "It just protects it from the Sun," he says. At this point he's getting really aggravated that I'm not buying his wisdom and more so when I tell him, "it's not going to happen" when he tells me to throw some pucks in the pool because he's too lazy to do the repair the same day.

    I guess that's my rant. Luckily I have a submersible pump I can use to circulate the pool water a little bit. I'm going to put the FC up to about 12 before he starts work tomorrow so it can "coast" for a couple of days.
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    Re: Why is basic water chemistry so controversial?

    thats just what he knows, and just think everyone used to "KNOW, the earth was flat" and we are the center of the universe

    12 or 15 FC sounds like a great place to start... brush it once or twice a day and you should be good
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    Re: Why is basic water chemistry so controversial?

    It's also what he has been taught because in spite of the chlorine / CYA relationship being definitively determined since at least 1974, the pool industry continues to pretend it does not exist. The "CYA doesn't matter; only FC matters" mantra is a myth that has been repeated so many times and for so long that even many people working for the manufacturers actually believe it. What was originally deceit has turned into permanent ignorance.

    It's not just affecting what pool professionals do for residential pools, but it affects what goes on in indoor commercial/public pools where they believe that because there is no sunlight, no CYA is needed. So people are needlessly exposed to at least 5 if not 10 times the active chlorine concentration than necessary and as a result swimsuits, skin, and hair get oxidized that much faster and disinfection by-products get created faster as well for an overall swimming experience that hurts the industry. My wife now refuses to swim in the local indoor commercial community center pool during the winter after her swimsuits degraded every season and skin and hair felt much more of the effects from the chlorine in 1-2 ppm FC with no CYA compared to our own pool with 3-6 ppm FC and 40 ppm CYA. We now spend gobs of money gas heating our pool during the winter.
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    Re: Why is basic water chemistry so controversial?

    I know around here, the professional pool people who use chlorine gas to chlorinate do have the pool's cya on the high side, maybe even as high as 80, because it works for them to be able to really get the chlorine level high when they service it, and then the chlorine level doesn't get too low before they service it again the next week. I myself prefer to have mine at least 40-50 this time of year, because I have to skip days due to my work schedule, and this way I put the chlorine high if I know I'll have to skip a day, and then it doesn't get too low before I can dose it again. That being said, I think there's a HUGE racket about the denial of the CYA - chlorine relationship because the pool industry makes more money that way.

    - - - Updated - - -

    Oh, and 12 should be good. I got mine up to 12 with 40 CYA on Friday night, had to skip Saturday and yesterday, and it was 5 this morning. And that's in the middle of the Arizona desert in full sunlight in the middle of the day.
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    Re: Why is basic water chemistry so controversial?

    Yes, pool service people who can only visit a pool once a week and not daily need to have the CYA higher (usually 100 ppm if not higher) to have the chlorine last through the week (unless they use Trichlor tabs). They then raise the FC to 14 ppm so that it ends up no lower than 4 ppm FC at the end of the week.

    Your 12 ppm FC ending up at 5 60 hours later would be a loss rate of 1 - (5/12)^(1/(60/24)) = 30% per day which isn't so terrible. For one day this would go from 6 ppm FC to 4.2 ppm FC.
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    Re: Why is basic water chemistry so controversial?

    It is not controversial...problem is if your pool gets a llitle out of whack the first thing most people do is take a sample to a pool store and follow their orders. I believe most people wont chug in bleach and hope its ok. I use a lot of bleach and polyquat. Ive got only 13k gallons and in July I wouldn't hesitate using 5 gallons a week. Some say overkill but its just bleach.
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    Re: Why is basic water chemistry so controversial?

    Quote Originally Posted by sbcpool View Post
    Then he tells me that "chlorine lock is a myth" and that you don't need more chlorine with higher stabilizer levels. "It just protects it from the Sun,"
    umm...so ask him how he thinks the CYA protects the chlorine from the sun? its not some magic umbrella going over the pool, lol. there is just no point in arguing chemistry with people that don't know (or want to) anything about chemistry.

    you should print out a few of the more technical posts from chemgeek and hand them to him next time he is over, lol
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    Re: Why is basic water chemistry so controversial?

    Quote Originally Posted by dansdad View Post
    It is not controversial...problem is if your pool gets a llitle out of whack the first thing most people do is take a sample to a pool store and follow their orders. I believe most people wont chug in bleach and hope its ok. I use a lot of bleach and polyquat. Ive got only 13k gallons and in July I wouldn't hesitate using 5 gallons a week. Some say overkill but its just bleach.
    It might be cheap, but you want to be able to swim in the pool without getting chemical burns. 5 gallons is a lot of bleach for a 13k gallon pool.

    - - - Updated - - -

    Quote Originally Posted by DaninFLA View Post
    umm...so ask him how he thinks the CYA protects the chlorine from the sun?
    Maybe CYA floats on the surface and protects the chlorine below
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    Re: Why is basic water chemistry so controversial?

    did somebody here ever do a controlled test to show the actual algae growth rate difference between two batches of water at say FC 3ppm, but with substantially different CYA (all other factors being equal/controlled)?

    I'm a no-doubt TFPC supporter and user, but the CYA chart started as somebody's "best guess chart", and while it's obvious to us there's a difference, I didn't know if there was a demo to point to.
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    Re: Why is basic water chemistry so controversial?

    5 gallons of 8.25% bleach in 13,000 gallons is 33 ppm FC so nearly 5 ppm FC per day which is quite high and unusual. You certainly wouldn't want to add that much at one time (unless you were doing a SLAM with high CYA).

    As for FC/CYA experiments with algae, there weren't explicit experiments done with that. If that were to be done, one would need to use worst-case conditions with plenty of algae nutrients and optimum temperature and sunlight. What we have seen instead is numerous reports of failures and if you were to track those you see that the highest FC/CYA ratios for those failures line up just under the recommendations in the Chlorine/CYA Chart. This is why we lowered the FC/CYA level for SWCG pools because we consistently saw that those pools' failures were substantially lower than those in non-SWCG pools.

    The original Best Guess chart was done by Ben Powell and it was mostly, but not exactly, correlating with the science though he used broad range categories so it could fit depending on what you chose within the range. I settled on starting with a midpoint fit and created a new chart consistent with the science that determines the active chlorine (hypochlorous acid) level.

    As for scientific papers consistent with the FC/CYA ratio itself or more specifically where the active chlorine level is the relevant factor and not FC alone, these are listed in the "Chlorine/CYA Relationship" section of the thread Certified Pool Operator (CPO) training -- What is not taught. All of the papers but one are consistent with chemical theory. The one that is not is the sole paper that looked at algae. It made no sense whatsover since the mechanisms for killing algae were no different than those killing bacteria, inactivating viruses and protozoan oocsysts, or oxidizing chemicals and is inconsistent with what we've seen from reports on this and other forums. Their paper shows green algae killed at 2 ppm FC at any CYA level up to the maximum 200 ppm CYA they used and that 1.5 ppm FC didn't kill the algae at any CYA level even 0 ppm and we know this isn't true in real pools. My best guess is that the growth media they used for the algae had ammonium compounds in them so that when they took the algae and added chlorine to it, they ended up with monochloramine which resulted in kill rates that were independent of CYA level (though the paper claims the growth medium was made to be chlorine demand-free). They also didn't measure kill rates, but mostly looked for binary complete kills with the way they did their tests. So maybe the algae itself had a chlorine demand of around 1.5 ppm so it would take at least that much for a complete kill. I tried to contact the authors of the paper, but never got a response.

    The good news with the SWCG pools has been that their much more consistent and continuous dosing has shown that the 5% FC/CYA ratio is truly near the edge when algae nutrients are high. Between that control and use of accurate FAS-DPD tests, it's clear that the algae inhibition level is reasonably accurate. The non-SWCG pool 7.5% FC/CYA ratio probably has more fudge room in it but not a lot. Also, these algae inhibition minimum FC/CYA levels are only for green and black algae, not yellow/mustard algae. My best guess from the algae paper and pools with yellow/mustard algae is that it takes roughly twice as much chlorine to kill this algae so the minimum FC/CYA ratio would be closer to 15% to keep that algae from growing.
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    Re: Why is basic water chemistry so controversial?

    I'm never lucky enough to get 8.25% way lower than that. And I do test with my k-2006 so I'm aware of what it is and I will say its high but not ridiculously so. I watch it I pour it in at night not morning and I will admit I hate the thought od tackling algae its a real pain. I used to buy chlorine from a pool store and it was high in chlorine and I didn't put in anywhere near as much but since I've been using bleach sometimes is great sometimes not so. I just check with the big K to see where I am and so far so good. I had to double check my post its not gallons its mostly 4. Some may think that is still too high but if I always 8.25% it would be different
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    Re: Why is basic water chemistry so controversial?

    If you're buying dollar store bleach I could see needing 5 gallons. Some of that stuff is mixed at 1% and might be old enough to be less than that. The big tip off to a bleach with low chlorine is that you can't find the concentration anywhere on the label. It's like when stores advertise sales as 10% off, or $10 off without ever giving you a price. They know if you had the information you wouldn't buy.
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    Re: Why is basic water chemistry so controversial?

    Let's look at it this way..... all of a sudden everybody knows the CYA/Chlorine relationship and believes it!

    You run a pool service and have all of your customers set up on a once a week visit. You, now, realize that powder and pucks are bad ju-ju, so you switch to liquid chlorine.....

    How will that affect your business? Same scenario, but you own or work in a pool store. How does that change your operation and/or bottom line?

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    Re: Why is basic water chemistry so controversial?

    Quote Originally Posted by sbcpool View Post
    I just had a run-in with a pool repair guy. Unfortunately I can't fire him because he's working on behalf of my insurance company.......
    You should check that with your insurance company, I know with mine, if I'm not happy with a contractor I can notify them and they will have a different contractor come out.

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    Re: Why is basic water chemistry so controversial?

    Quote Originally Posted by ewkearns View Post
    You run a pool service and have all of your customers set up on a once a week visit. You, now, realize that powder and pucks are bad ju-ju, so you switch to liquid chlorine.....
    Although I can't speak for the entire industry, I can vouch that you can run a weekly service with full knowledge and acceptance of everything taught here. There is nothing at all wrong with trichlor, as long as you are aware of what they do to the water. If done in a way that minimizes trichlor use and accounts for regular water changes then a weekly service absolutely can function within the knowledge that is learned here. It isn't really TFPC, more using traditional methods but accounting for their shortcomings.
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    Re: Why is basic water chemistry so controversial?

    That is the position that my PB took.... rationalizing it by noting that water was cheaper than anything else I was using to dose the pool.

    I don't think it ever registered with him that regular water changes were, in effect, throwing away a lot of purcha$ed chemicals, pumping water to waste, to make the water change...

    So, maybe it can be done, but I don't think it can be done economically....

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    Re: Why is basic water chemistry so controversial?

    There are things to consider besides the economics as well. In areas without a lot of water, what value do you place on having a river that flows as opposed to rivers that are sucked dry before they reach their destination? Is there a dollar value for that? What about leaving enough water to drink next year if there isn't enough rain or snow? It seems to me incredibly short-sighted to waste thousands of gallons of water today just because we're too lazy to change the way we manage our pools, and it doesn't seem to me like the right thing to do to consider nothing but our own personal financial cost of wasting a shared resource - especially one critical to life.
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    Re: Why is basic water chemistry so controversial?

    Quote Originally Posted by sbcpool View Post
    There are things to consider besides the economics as well. In areas without a lot of water, what value do you place on having a river that flows as opposed to rivers that are sucked dry before they reach their destination? Is there a dollar value for that? What about leaving enough water to drink next year if there isn't enough rain or snow? It seems to me incredibly short-sighted to waste thousands of gallons of water today just because we're too lazy to change the way we manage our pools, and it doesn't seem to me like the right thing to do to consider nothing but our own personal financial cost of wasting a shared resource - especially one critical to life.
    Great post ^
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