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Thread: Domestic pool turnover rates

  1. #11
    mas985's Avatar
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    Default Re: Domestic pool turnover rates

    Quote Originally Posted by Teapot
    I wish Marks report was more scientific, with proper turbidity test carried out and a particle count to see what was really in the water. If the pump is off the debris sinks but it doesn't show until it's stirred up. Since doing this the water is much clearer 0.5-1 NTU and there is no dirt or debris to stir up.
    The study seems pretty clear to me which states that they SAW no observable difference in water quality after 2 hours. If the debris sinks, then a vacuum can easily remove it without "stirring it up". The only time I have heard of someone having an issue like you are describing is when they just killed a bunch of algae and it sunk to the bottom. That debris is very light weight and can be stirred up easily but when cleaning up algae after it is killed, you should be running 24x7 anyway. But that should not happen very often if you follow the methods taught here.


    Quote Originally Posted by Teapot
    As I said chlorine will kill what in can in under a minute, that would be lots of different bacteria, virus's etc including algae spores so that's the job done except for chlorine resistant types, like Giardia and Cryptosporidium and oocysts which need filtering out (this depends on the filtration being good enough and may also need flocculent. Generally the pumps are too big and the filters too small to achieve great filtration, eyesight is too bad to judge.
    Why only a minute? Chlorine does not stop killing after one minute, it should continue killing these things if the level is set properly.



    Quote Originally Posted by Teapot
    Gage and Bidwell's paper on water turnover and dilution says after 1 turnover 63% of the water has been filtered, by my action I get a 6 hour turnover and that filters 4 times in 24 hours so 98% of the water is filtered.
    So what? Again, there is no good reason to filter the water at any specific turnover rate. It just doesn't matter to sanitation. Aesthetics, perhaps but only to some.



    Quote Originally Posted by mitchryan912
    What considerations would increase that run time? We have debris from out arbor vitae trees falling into the pool all the time, and we can't be out there manually skimming all the time. Would just 2-4 hours per day on high be enough and then a good chunk more on low be OK?
    Removing floating debris and debris that has sunk to the bottom of the pool is entirely up to you. It is only based on your personal preference.

    Some people like me could care less if there is a little debris in the bottom of the pool or even on the surface. My priority is to minimize run time.

    Other people are quite anal about a pristine pool and thus require lots of run time so every spec of dirt and debris are immediately removed from the pool. However, this desire sometimes comes at a large cost.
    Last edited by mas985; 07-26-2015 at 06:20 PM.
    Mark
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  2. #12
    CarlD's Avatar
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    Default Re: Domestic pool turnover rates

    I, for one, like a pristine pool. See above ^^^

    But as I pointed out that is NOT Mark's point. My reasons for running longer than is necessary for sanitation are valid, but not relevant to his point. They are separate issues.
    Carl

  3. #13
    Anonymous [GDPR] European in the UK Guest

    Default Re: Domestic pool turnover rates

    Quote Originally Posted by mas985 View Post
    The study seems pretty clear to me which states that they SAW no observable difference in water quality after 2 hours. If the debris sinks, then a vacuum can easily remove it without "stirring it up". The only time I have heard of someone having an issue like you are describing is when they just killed a bunch of algae and it sunk to the bottom. That debris is very light weight and can be stirred up easily but when cleaning up algae after it is killed, you should be running 24x7 anyway.

    Yes but the human eye can't see very much, if anything smaller than 30 microns. You cant see electricity so is that safe then? Although thankfully rare chlorine resistant strains of bacteria do happen so filtering them out is necessary and if you filter at that level very little chlorine or chlorine reactions are needed to keep the pool in top condition. If what I wrote was more expensive than normal I could understand the objection but I achieve these results on a lot less, call it a bonus.


    Why only a minute? Chlorine does not stop killing after one minute, it should continue killing these things if the level is set properly.
    Now that is a miss understanding, chlorine doesn't stop killing of course but it can terminate most common bacteria and virus etc in under a minute. That's why when the level of chlorine present is sufficient then high filtration rates are not needed as the report also showed. In fact because most people have pumps to big for there filters they are wasting more electricity breaking up whats filtered into smaller parts that just pass through the filter.



    So what? Again, there is no good reason to filter the water at any specific turnover rate. It just doesn't matter to sanitation. Aesthetics, perhaps but only to some.
    Yes agreed, I just made observations about the rate Not a recommendation.



    Removing floating debris and debris that has sunk to the bottom of the pool is entirely up to you. It is only based on your personal preference.

    Some people like me could care less if there is a little debris in the bottom of the pool or even on the surface. My priority is to minimize run time.
    My priority is to minimise electricity bills, and cleaning all the other parts come as a bonus. My pool is let to paying guests they can be quite anal.

    Other people are quite anal about a pristine pool and thus require lots of run time so every spec of dirt and debris are immediately removed from the pool. However, this desire sometimes comes at a large cost.

  4. #14
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    Default Re: Domestic pool turnover rates

    Teapot:
    Are you a commercial pool operator? "My pool is let to paying guests..." makes me infer that you are.

    Anyone in the pool business is required to very specifically state that in their signature. If you are in the business of SELLING "Passivpool" then you must explicitly say so. If you are not and are merely singing its praises in your sig, that's OK.

    But again, if you are a commercial pool operator or in the pool biz you must say so--and abide by our AUP for pool pros.
    Carl

  5. #15
    chem geek is offline Lifetime Member Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
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    Default Re: Domestic pool turnover rates

    Quote Originally Posted by Teapot View Post
    The chlorine kills what it can in under a minute, what isn't killed by chlorine has to be filtered out. How quickly should this be filtered out? should it be a hour or 8 hours? If the filtration isn't good enough then the whole lot is just recirculated so you spend on electricity achieving very little.
    :
    1. The dirt and debris actually go into the skimmers because the system is running so a lot less makes it to the bottom which is what happens when a system is off.
    Quote Originally Posted by Teapot View Post
    As I said chlorine will kill what in can in under a minute, that would be lots of different bacteria, virus's etc including algae spores so that's the job done except for chlorine resistant types, like Giardia and Cryptosporidium and oocysts which need filtering out (this depends on the filtration being good enough and may also need flocculent. Generally the pumps are too big and the filters too small to achieve great filtration, eyesight is too bad to judge.
    :
    If the system is running 24/7 then the detritus gets into the skimmers not to the bottom of the pool.
    You don't filter out pathogens. Bacteria and viruses are to be killed by chlorine in the bulk pool water to prevent person-to-person transmission. It's only the protozoan oocysts that take a lot longer, especially for Cryptosporidium parvum that for practical purposes isn't killed by chlorine (at normal levels), but that is very uncommon in residential pools. Those Crypto spores are also too small to get caught in sand or even most cartridge filters without coagulants. In the U.S., the CDC Model Aquatic Health Code (MAHC) proposal requires the use of supplemental systems such as ozone or UV in the circulation system to kill Crypto in high-risk venues. There are some other unusual pathogens that aren't killed readily by chlorine such as iron bacteria and of course if one isn't diligent about maintaining the proper FC/CYA level then biofilms can form and be more difficult to remove.

    If you are running on low speed, then unless you have an outstanding circulation system with many returns, you won't get great skimmer action. At low flow rates one simply doesn't have enough water flow to move leaves around the pool and into the skimmer quickly enough. This depends, of course, on pool design. Some pools will work OK at low speeds, but many won't since they were designed originally for high speed pumps so the placement and number of returns is pretty paltry when run at low speeds.

    I agree with you though that if you don't run during some times throughout the day (not necessarily 24 hours, but on and off so the "off times" aren't too long, then that will help prevent surface debris from getting water logged and sinking. Of course, with a pool sweep such items can get collected from the bottom so I'm not sure why that's a problem. If you don't have a pool sweep, then what you propose keeping the water moving at the surface longer would make some sense, with the caveat of sufficient flow to actually move things towards and into the skimmer.

    By the way, we aren't proposing to run at high speeds for long times. If a pool can run at low speeds all the time that the pump is on with reasonable skimmer action, then great. What Mark is saying is that whatever the pump speed is, it doesn't usually need to be run for as long as people think. You can run your low speed for perhaps hours over the 24 hour period and have great water clarity. If one needs some skimmer action, then perhaps one needs an hour every 8 hours at high speed for that. And so on. In other words, use the low speed whenever possible and use the shortest times to achieve the desired result. That results in the lowest energy usage to achieve the desired water clarity and skimming action.

    As for low TA levels, that has been suggested for many years to have more stable pH. I don't remember when Ben suggested it but it was a long time ago. Just remember that if you have a plaster pool then you need to have a higher pH target and/or higher CH to compensate for the saturation index to saturate the water with calcium carbonate to protect the plaster.

    Quote Originally Posted by Teapot View Post
    Gage and Bidwell's paper on water turnover and dilution says after 1 turnover 63% of the water has been filtered, by my action I get a 6 hour turnover and that filters 4 times in 24 hours so 98% of the water is filtered.
    See the section "Turnover Rate and Law of Dilution" in the first post of the thread Certified Pool Operator (CPO) training -- What is not taught. The Gage and Bidwell model does NOT tell you how much of the pool water has "seen" the filter. It is less than that because they assume a specific amount of contamination introduced once per day and then calculate the clarification percentage. He says that one turnover has only 42% clarification. Fortunately you aren't quoting that number and are instead quoting the correct 63% number, but that has nothing to do with Gage and Bidwell. So your numbers are correct, but you shouldn't refer to Gage and Bidwell since that can be confusing.

    Quote Originally Posted by Teapot View Post
    Yes but the human eye can't see very much, if anything smaller than 30 microns. You cant see electricity so is that safe then? Although thankfully rare chlorine resistant strains of bacteria do happen so filtering them out is necessary and if you filter at that level very little chlorine or chlorine reactions are needed to keep the pool in top condition. If what I wrote was more expensive than normal I could understand the objection but I achieve these results on a lot less, call it a bonus.
    Believe me, you won't be filtering out bacteria. Most bacteria are going to attach themselves to surfaces or to particles because they generally only reproduce affixed and not when free-floating. You can't rely on filtration for most pathogens. Oocysts and spores are difference since they generally don't attach and instead float through the water so will generally get circulated. Though the same is also true for viruses, filters won't capture them (without coagulation).

    Mark has always said that using low-speed (or the lower speeds of variable speed) pumps saves a lot of energy and you agree with that. So the only question left is how long to run at this lower speed. This is where you two differ, but I think would agree that you need to run at higher speed part of the time if that is necessary to achieve a specific goal such as getting proper skimmer action and that clearly depends a lot on specific pool design.

    Then the question becomes how to space out this higher speed over the day and how long to run at low speed and how to space that out. Here is where you differ where Mark is saying you don't need even a full turnover in most residential pools whereas you are going for 24/7 filtration and have more turnovers. That obviously uses more energy than if you cut back your total runtime, even if you spaced it so that you didn't have long "off" periods to still achieve your goal of having mostly skimmer action rather than picking up debris in a pool sweep.

    My pool runs for roughly one turnover per day but not because of any filtration need but rather because my solar system runs at 48 GPM and is on longer, usually 4-6 hours per day depending on the time of year. The pump is on low speed with 26 GPM for the other 2-4 hours for a total of 8. With my 16,000 gallon pool this translates into 1.11 to 1.275 turnovers. My pool looks like the following:





    and a photo of one of my main drains at night is the following:



    Since I only have a cartridge filter, I'm sure I could get even better water clarity but it's plenty fine for me as it is. The only thing that might improve from even longer circulation is reducing the number of floaties one sees in the pool light assuming that such floaties aren't just in a "dead" pattern going around the pool (i.e. a bad circulation pattern that extra circulation time won't fix). I have a pool cover that keeps the pool relatively free of debris though it is used nearly every day so during that time stuff does get blown in. I do clear the skimmer basket, pool sweep bag, and pump basket of debris at least weekly (skimmer basket sometimes more frequently, especially during fall).
    15.5'x32' rectangle 16K gal IG concrete pool; 12.5% chlorinating liquid by hand; Jandy CL340 cartridge filter; Pentair Intelliflo VF pump; 8hrs; Taylor K-2006 and TFTestkits TF-100; utility water; summer: automatic; winter: automatic; ; PF:7.5

  6. #16
    Anonymous [GDPR] European in the UK Guest

    Default Re: Domestic pool turnover rates

    Quote Originally Posted by CarlD View Post
    Teapot:
    Are you a commercial pool operator? "My pool is let to paying guests..." makes me infer that you are.

    Anyone in the pool business is required to very specifically state that in their signature. If you are in the business of SELLING "Passivpool" then you must explicitly say so. If you are not and are merely singing its praises in your sig, that's OK.

    But again, if you are a commercial pool operator or in the pool biz you must say so--and abide by our AUP for pool pros.
    Hi Carl,
    No I am not a commercial pool operator, I have a holiday home which guest can use. When I joined, Ben and I discussed this and he looked at my place. I also made it known to Ben that I do work in the pool industry but no mention was made of needing to do anything else but he warned me not to sell and I am not. I am sharing information. I am however shocked that you have handed out warnings which to me, seem to be for actually having an opinion and sharing it.

    Ben had an opinion, he started this forum because his opinion was different to others, some have copied his idea and run off with it.

    Mark's information has always been helpful, I am not crossing that line and as you wished the topic is now in the China Shop although saving energy is main stream and every one want's to save money, that's why they are on here and not down the pool store?
    I would prefer it if you feel I have broken a rule to point that out without administering a warning, maybe an email?

  7. #17
    Anonymous [GDPR] European in the UK Guest

    Default Re: Domestic pool turnover rates

    Thank you Richard,
    Yes whilst I do run 24/7 it's due to having lots of trees around, not everyone will, but some who post on the forum do so different ways of running for given situations. I am not saying everyone has to run 24 hours and if you are willing to accept less, fine but has anyone explored what happens if you do run 24 hours, no because of the cost. My cost are low, very low, It cost me less to run 24 hours than most other pools cost for 2 hours. That's where the study has been going on.

    Just like Mark's study on turnover it appears we need a lot less turnover than previously thought. If I had less trees I would almost certainly reduce the run time but as I said you can only skim the surface if the equipment is running.

    Yes I appreciate what can and cannot be filtered but even biofilms break free and normal filtration doesn't catch them it circulates them.

    There is as you point out a point at which the water flow is insufficient to achieve a skimming action and so there is a flow at which we can't go any lower in my pool that appears to be 23GPM. Being an oval pool it's more hydrodynamic than a rectangle and you hit the spot with the return jets. Too many lazy pool builders do not know or plan the placement of skimmers or returns or even the number of returns. I was able to sell my robot as running as I do it wasn't needed even with the number of trees I have but I have to empty the skimmers more frequently because that's where it all ends up and on low energy pumping the flow can drop and the automatic sensor will cut off the pump if water stops flowing to protect the pump. As you said pool equipment was never made with efficiency in mind.

    Your pool looks good Richard but there is extra electricity being used for the booster pump for the pressure side cleaner, I just use a Pool Blaster max now days although I can of course use the old vacuum head and hose should anything happen but it hasn't and less work is required now to look after the pool.

    Just sharing what I have spent my time doing, and the turnover thing for domestic pools is a red herring but better to have a finer filtration and collect stuff which works even better on slow filtration than fast. We are all energy savers but single speed pump pool owners may hopefully gain something.

    Regards to all on the Pool Forum in case Carl doesn't like what I have written and issues a 3rd warning.

  8. #18
    CarlD's Avatar
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    Default Re: Domestic pool turnover rates

    Ben is not here to make judgements or correct errors I may make as a moderator. There are only myself and WaterMom. We have to make decisions about appropriate posts ourself, without Ben.

    If you have an understanding with Ben, that's fine, but your posts made it sound like you are a pro in the business--and we have definite rules about that. As I said, if you are not a pro, those rules don't apply.

    I'm not sure I have access to your eMail--Ben keeps many powers to himself as is his right--and private messaging is shut down. But I do have other powers to ensure our rules are followed and decorum is maintained. I'd prefer not to use them, and rarely have over the years.
    Carl

  9. #19
    Anonymous [GDPR] European in the UK Guest

    Default Re: Domestic pool turnover rates

    Understood Carl, Please point me to your rules for people in the industry. I am in the industry as I told Ben, if there is something I should do, add to my signature etc, please let me know but I am NOT selling anything. If you need to email me for any reason it's john@le-pre.co.uk
    Hope we can continue.

  10. #20
    CarlD's Avatar
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    Default Re: Domestic pool turnover rates

    Carl

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