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Thread: How To Determine Water Turn Over Rate, flow rate turnover

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    Join Date
    Jun 2007
    Location
    Atlanta, GA
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    How To Determine Water Turn Over Rate, flow rate turnover

    How could I estimate the amount of time it takes to send all of the water in my pool through the filter one time. I have a 15,000 gallon pool, 1.5HP (1.1kW) sta-rite pump and a Sta-Rite system 3 filter. The filter says max flow rate is 125 GPM, which I guess is gallons per minute. If the filter is my limiting factor, then that is 2 hours to turn over all the water in my pool. I don't know the flow rate of the pump. I am going to assume that the sizing of pipes, holes, etc is as perfect as can be because of the installer's reputation in the area.

    Furthermore, I'd like to know the minimum number of times I need to turn over the water in the pool for each 24 hour period, assuming light use and little sun (less than 1 hour exposure a day) with a SWG, FC 3-4.

    Finally, if the pool is closed over night, is there any reason to circulate the water at all during the night if the water turned over enough times during the day? Or would running even a bit over night optimize sanitation because the water would not sit for still for 16 hours (or so) straight?

    I'm looking for some guidance to start with which I can then tweak for my specific usage. I have a Jandy control, so scheduling is not an issue. I do factor in that I add chemicals in the evening or morning and solar heating is optimal between noon and 5pm.
    Location: Atlanta, Georgia.
    Pool: 15,000 gallon 32'x18', 3'-6' deep in-ground gunite pool, Sta-Rite 3 125 GPM 2-filter cartrige, 1.5 HP Sta-Rite pump, solar heater, Goldline SWG, Jandy controls, opaque automatic CoverStar solar pool cover, 3 waterfalls (not from spa).
    Spa: 485 gallon in-ground square acrylic over fiberglass suspended over gunite Sunset brand spa, isolated system, natural gas heater, 2-speed (4hp/11hp) main pump, 3hp booster pump, chlorine sanitized.

    To my pool store owner, nothing is more important than my pool and my money.

    Richard's PoolEquations Spreadsheet

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    duraleigh's Avatar
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    Apr 2007
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    Re: How To Determine Water Turn Over Rate, flow rate turnover

    itabb,

    Welcome. You'll find this a good place to get good answers....most better than mine. (yes, gpm = gallons per minute)

    Generally, turning your water over 2-3 times daily is considered good practice. If you can find your pump online with sta-rite, you can probably find a "pump curve" which will show you how many gpm your pump is capable of producing factoring in a given amount of "head" (resistance). Know ing the exact resistance in your system is usually quite troublesome so many of us simply use 40-50 as a good average for most pools. My bet is you'll probably come in somewhere around 70-85 gpm with that pump.

    Now, knowing roughly what your pump produces in gpm, it's pretty easy to calc how much run time is needed to get that 2-3 turns daily that you're looking for.

    I think it makes good practical sense to divide that run time into two sessions daily....some even use three. You're off to a great start and have a good grasp of the issues involved. I hope this helps you tweak your system a little. Happy Swimming.

    BTW, that's a very nice filter for that system. filtering capacity greater than the pump can produce is always, always a desirable feature.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Welcome to TFP!

    If you want to figure out your flow rate you should read this thread. Casually I would guess that it is between 40 and 80 GPM. The pump is normally the limiting factor.

    The basic rule of thumb is to aim for one turn over a day. What really matters is how the water looks, so you can adjust up or down from there to balance the appearance of the water with the expense of running the pump. You also need the pump running for the solar system, so it is possible that that will be the constraint.

    Running for several hours during the day and leaving the pump off at night is fine. You will want the pump running for at least an hour or so after you add chemicals.
    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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