How To Determine Water Turn Over Rate, flow rate turnover

itabb

Well-known member
Jun 22, 2007
71
Atlanta, GA
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.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
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.
 

JasonLion

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May 7, 2007
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Silver Spring, MD
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.