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Thread: Trying to determine what my systems flow rate is and what it should be.

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    rosslamon's Avatar
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    Trying to determine what my systems flow rate is and what it should be.

    I'm trying to calculate just how many GPM my system is putting through my filter. I have 1 1/2 inch piping. My best guess is my skimmer has about 6 90 degree turns and my main drain has 4 90 degree turns before they combine. After that they have 3 90 degree turns before reaching my multiport. These are pumped by my 2hp pump. Average clean psi is 16. I'm not sure where to start with these calculations. I want to know how many GPM I'm putting through my filter. Hayward recommends 45 gallons per minute with 1 1/2 inch piping, but I'm not sure if I'm over that or if that's a limit or what exactly I'm working with. Obviously I just want to filter as much water as quickly as possible. All of this is with the purpose of figuring out my turn over time. I've tried to search the forums and the internet in general and everything I seem to be finding is aimed at specific peoples problems. Thanks for any help! Here's a picture of my setup. (ignore the dangerous looking timer/wiring. That's a project I'm working on.)
    My pool: ~22.6K gallon. 16'x32' with 8 foot deep. 10 year old vinyl liner (prayers)
    Century A.O. Smith UST1202 56J C-Face 2 HP Single Speed Up Rated Pool Filter Motor, 19.6/10.4-9.8A 115/208-230V
    Hayward S244T ProSeries 24" In- Ground Sand Pool Filter

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    Re: Trying to determine what my systems flow rate is and what it should be.

    As hard as you think it might be just order one of these for your return Yes they are expensive but it will tell you exactly what your looking for..

    TFTestkits.net
    Pool: Intex 16x32 15000 gal, 2 speed 340042, Pentair CC320 Filter, CircuPool SJ45 Salt System, Intermatic PE653RC; Hot Tub: 650 Gal SWG Megachlor
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    Re: Trying to determine what my systems flow rate is and what it should be.

    If you are just looking for a 1 time measurement and don't want to spend the money on the flow meter, you have a threaded union on the output of the filter, take it loose and see if you can gently push the connecting return line to the side enough so you can direct the output into a 5 gal bucket or even better a larger container, does not mater what as long as you know the volume. have someone turn the pump on while you time how long it takes to fill and do the math. It will be a bit messy and not perfect but should be good enough to get close.
    12,300 Gallon, IG PebbleFina, 3 ft sheer, 2 Jandy nicheless LED lights, Jandy Pro 1.5HP VS pump (A.O. Smith Motor), PB4-60 Booster pump, Polaris 280, Jandy cv340 cartridge filter, Zodiac Z4 control panel W/iAquaLink, Stenner pumps for chlorine & MA connected to WiOn WiFi switches, TF-100. You can support TFP with AmazonSmile just click the link!

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    mas985's Avatar
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    Re: Trying to determine what my systems flow rate is and what it should be.

    If the water bypasses some of the plumbing, the flow rate will be higher than normal.

    The flow rate will likely be far more the 45 GPM but that really shouldn't be an issue. That filter can handle close to 80 GPM and the design flow rate is 62 GPM. Where did you come up with the 45 GPM?

    I can get fairly close to the exact flow rate with the following information.

    Clean Filter Pressure: 16 PSI

    Pump make/model: SuperPump 2 HP

    Pump height above water level:

    Suction and return pipe lengths (pool to pump):



    All of this is with the purpose of figuring out my turn over time.
    Turnover doesn't matter. Please read this: Pool School - Determine Pump Run Time
    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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    Re: Trying to determine what my systems flow rate is and what it should be.

    Quote Originally Posted by mas985 View Post
    If the water bypasses some of the plumbing, the flow rate will be higher than normal.
    I realized that on my way home thinking about what I sugested while I was siting in traffic, glad you have a solution.
    12,300 Gallon, IG PebbleFina, 3 ft sheer, 2 Jandy nicheless LED lights, Jandy Pro 1.5HP VS pump (A.O. Smith Motor), PB4-60 Booster pump, Polaris 280, Jandy cv340 cartridge filter, Zodiac Z4 control panel W/iAquaLink, Stenner pumps for chlorine & MA connected to WiOn WiFi switches, TF-100. You can support TFP with AmazonSmile just click the link!

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    rosslamon's Avatar
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    Re: Trying to determine what my systems flow rate is and what it should be.

    Quote Originally Posted by mas985 View Post
    Turnover doesn't matter. Please read this: Pool School - Determine Pump Run Time
    i must have missed that day in pool school. Thanks a lot for the link. That's exactly what I was trying to figure out. So I just need to run it enough to disperse chlorine. Everything after that is for aesthetics. Which will still mean a considerable run time for me as I have trees hanging directly above the pool, but now I know it will still be safe for use as long as chemicals are balanced.
    My pool: ~22.6K gallon. 16'x32' with 8 foot deep. 10 year old vinyl liner (prayers)
    Century A.O. Smith UST1202 56J C-Face 2 HP Single Speed Up Rated Pool Filter Motor, 19.6/10.4-9.8A 115/208-230V
    Hayward S244T ProSeries 24" In- Ground Sand Pool Filter

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    Re: Trying to determine what my systems flow rate is and what it should be.

    Quote Originally Posted by rosslamon View Post
    i must have missed that day in pool school. Thanks a lot for the link. That's exactly what I was trying to figure out. So I just need to run it enough to disperse chlorine. Everything after that is for aesthetics. Which will still mean a considerable run time for me as I have trees hanging directly above the pool, but now I know it will still be safe for use as long as chemicals are balanced.
    I'm new here and still learning pool school too, and hadn't read the pump time article just yet. I'm glad you asked this question because I thought I had to go the same route, but now I know I don't. I haven't decided on how I'm going to feed my chlorine, but however I do it, I'm going to try to get enough into my pool in 4 hours so that I don't have to run my pump any longer than that. I don't have any trees to mess things up, so I'm excited to save some electricity and keep the noise down.

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    Re: Trying to determine what my systems flow rate is and what it should be.

    Easiest way is to install vacuum and pressure gauges on the equipment in the appropriate place. Multiple vacuum by 1.13 then the pressure by 2.31 add the numbers together and use the pump curve to find the g.p.m.


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    mas985's Avatar
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    Re: Trying to determine what my systems flow rate is and what it should be.

    That is one of many ways to determine flow rate but there are other easier ways and one specifically that only requires filter pressure.

    But again, knowledge of flow rate isn't all that important.
    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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