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Thread: How accurate is my turnover estimation?

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    How accurate is my turnover estimation?

    So the other day as I doing regular maintenance on the pool, I had a brilliant idea for measuring turnover in my pool. :P Noticing that my spa is essentially 2 differently sized cylinders, therefore easy to estimate volume, I thought all I have to do is isolate the spa and measure the time it takes to empty using a stopwatch.

    Would this be in any way accurate? I come up with an estimation of about 5.5 hours for one turnover.

    Considering I normally draw from the skimmer only, how much would the added distance to the spa( approximately 17ft ) affect turnover rate?
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    JasonLion's Avatar
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    Re: How accurate is my turnover estimation?

    The plumbing to the spa is very different than the plumbing to the pool, so the flow rates are going to be different. Almost invariably the flow rate to the pool will be lower. Your method does give you a rough approximation, say within a factor of two, but it isn't going to give you a number precise enough to be useful. On the other hand, that might be enough of a clue to plug into mas985's black box and get a number from him.
    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: How accurate is my turnover estimation?

    Quote Originally Posted by JasonLion
    The plumbing to the spa is very different than the plumbing to the pool, so the flow rates are going to be different.
    You mean because of the returns?
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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    JasonLion's Avatar
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    Re: How accurate is my turnover estimation?

    The corresponding pipes on the pool and spa are most likely different diameters, certainly different lengths, and will have different numbers and kinds of fittings, so the dynamic head is going to be different. A lot of the dynamic head is the same in both cases, pump, filter, main valve, etc, but there is still enough difference in the two situations that there will be noticeable flow rate differences.
    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: How accurate is my turnover estimation?

    I would guess that there is a formula for finding the turnover rate for a given pool and it's components. But is there a way to measure the actual turnover in my pool?
    Esther Williams 18'x33'x50" oval above ground
    Filter/pump being changed at this time
    Pentair model 320 auto chlorine feeder
    Taylor TF-100 test kit

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    mas985's Avatar
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    Re: How accurate is my turnover estimation?

    There are flow meters you can install in the plumbing which will tell you actual flow rate but accuracy is not all that great. I can usually get just as close or even better just by knowing the equipment and plumbing setup.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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