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Thread: Pump/filter run times

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    Oct 2007
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    Pump/filter run times

    I have a question concerning pump/filter runtimes, especially with respect to SWCG systems. It is recommended that the filter be run for at least eight hours when using a SWCG. Shouldn't this be rather tied to a minium number of turn-overs? What is gained by running for eight hours outside of the number of turn-overs?
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    Rockcrawler's Avatar
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    May 2007
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    Re: Pump/filter run times

    In my opinion in winter time you do not need to run your pump 8 hrs a day, Your right on with how many turnovers you want, as long as your clorine level it up where you want it and your pool is clean, I have experiemented with this, and in the winter time (El Paso pool stays open, water temp 50 degrees lowest it gets) (would probaly apply in Florida as well)I run my pool 2 hrs a day, with SWG on. In the summer, I need to run it about 8 hrs a day, because my clorine need is up and I have solar panels. If your clorine stays up where you want it then I would cut your pump time down to at least get one turn over in the witer time.

    Rob
    13,000 IG Plaster, 2hp whisperflo pump, 48 sq in pentair DE Filter, 1 skimmer, 2 eyeball outlets, 200 sq ft solar panels on second story, Auto Pilot SWG-36, Polaris ATV Cleaner

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    JasonLion's Avatar
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    Re: Pump/filter run times

    There are several factors operating here. First let us think about the pump without a SWG. Turnovers are just a rule of thumb guide to how much the pump should be run. During the summer, one turnover a day is usually enough, but some pools need more and some pools are fine with less. You can figure out a good pump run time by experimenting with different run times and seeing how they affect the water clarity. During the winter you can get away with much less pump run time than you have in the summer. The colder the water gets, the less circulation you need to keep it clean.

    Now add in the SWG and things change a little in some situations. The amount of chlorine produced by the SWG depends primarily on the combination of the percentage setting on the SWG and the pump run time. Within some range, you can trade off these two factors to get the same amount of chlorine produced. For example a SWG running at 25% for 4 hours will produce the same amount of chlorine as a SWG running at 100% for 1 hour. Normally you figure out what pump run time you need to keep the water properly filtered and then adjust the SWG percentage to get the amount of chlorine you need.

    Sometimes, the optimal pump run time turns out to be shorter than the amount of time it takes the SWG to produce the amount of chlorine you need, even when the SWG is set to 100%. In these situations, you need to run the pump longer to get enough chlorine into the water. This most commonly happens when you have a relatively large pump and a relatively small SWG. In practice what happens is that you get to a point where you need to turn the SWG percentage up above 100% and you can't, so instead you increase the pump run time.

    Oh, one more thing. In the winter you need less chlorine, as well as less filtering. In most cases, you can lower the pump run time as the water gets colder and lower the SWG percentage at the same time and still get enough chlorine into the water.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pump/filter run times

    The Pool School has an article that talks about turnovers based on pump HP.
    Doesn't seem to factor in pipe diameter tho... reading other stuff, it seems like
    there'd be a big difference between 1.5" and 2" plumbing.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Pump/filter run times

    The reason I posted this question was because of this article. In it the statement is made:
    Run your pump a minimum of 8 hours a day and adjust your cell output so your FC stays between 3-5 ppm. Even if you can produce enough chlorine with a short pump run time and higher cell output you will have fewer problems if you run the pump a minimum of 8 hours during the day.
    It just seemed to me a little confusing giving a pump run time with respect to chlorine generation. Perhaps this statement could be better explained in the article.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    JasonLion's Avatar
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    Re: Pump/filter run times

    The SWG balancing Pool School article advice is aiming for the ideal water conditions assuming a reasonably normal setup during the summer. Running the SWG any time there is significant sunlight is ideal for the SWG and the water chemistry and will work very well for many pools. But it might not be ideal for your pool, depending on several other factors.

    Running the SWG during the day, for the entire time there is direct sunlight on the pool, allows the total time the SWG is actually on to be minimized. Sunlight uses up chlorine. The lower the FC level can be while there is sunlight on the pool, without ever getting too low, the less chlorine you lose to sunlight.

    If you produce chlorine at the same time that it is being lost to sunlight, so the FC level remains nearly steady just above the minimum FC level, you use less total chlorine than if you build the FC level up high in the morning so it will still be reasonable in the evening after all the sunlight losses. Less chlorine lost means less total run time for the SWG and fewer side effects from having the SWG on.

    If the water is cold (below 60 degrees) then you run the pump less, a situation not considered in that article.

    If you have time of day electric rates and electricity costs significantly more during the day, then you will probably want most of your pump run time to be at night. That will mean that the SWG has to work a little harder and the other side effects of running the SWG, like PH drift, will be a little bit worse, but it will still be worth running at night for many people since they can save a lot of money on their electric bill that way.

    The same idea applies if you have a particularly large pump compared to your pool size and can get optimal filtering in just a couple of hours and the SWG still produces enough chlorine in just a couple of hours. Again, to save on electricity it becomes more important to run the pump less, and you put up with the minor disadvantages of having to run the SWG more.

    One of the big problems with swimming pool care is that what is going on is actually very complex. Because understanding every tradeoff is just too complex, we make up these "rules of thumb" that give you simple guidelines that are practical to follow. Unfortunately, it is impossible to come up with a set of simple rules that cover every situation. So you occasionally get conflicts, like the pump run time situation discussed above, where one rule says one thing and another rule says another thing and most likely neither of them are actually ideal in your particular situation.

    All that said, the article probably could be worded differently, so that it still encourages running the pump 8 hours during the day and also makes it clear that other tradeoffs might make over-ride that advice in some situations.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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