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Thread: A few random thoughts

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    Arrow A few random thoughts

    Did a new pool build last year, had it open for September and October before closing.
    Opening now. Water looks great but working to lower TA from over 200.

    A couple random thoughts.

    I have a variable speed pump.
    I set it to run at a 2100 RPM or so for 22 hours per day to keep the SWG flow high enough. SWG I have set for 40% production.
    Then for two hours a night I have it run at 3400 RPM for clean cycle.
    I'm still guessing on my GPM flow. I have 1.5" piping all around including at a bottle neck right before the pump.
    The other night I came back late from a travel trip and heard the pump screaming at the high speed.

    Here are my random thoughts.
    1. At 3450 RPM, my "guess" is that I'm at 75 GPM. But I'm suspecting I might be trying to push more water through than is really feasible and I'm just stressing the pump. Maybe I have a true limit on what's productive on the high end.

    2. SWG - I'm thinking of running my pool at a lower speed that what the SWG will generate at. Then run it at a middle speed for the SWG to work. So instead of running 40% for 16 hours, run 100% for 5-6 hours (or whatever it ends up needing). I'll tailor in the correct SWG production percentage to match once I have everything stablized.

    3. Skimmers. How do I know if they are actually doing anything? I have two skimmers and dual drain in the deep end (which goes to one 1.5" pipe for the drain. Each skimmer with dedicated lines. I know water flows through them, but with an auto-cover, is there main purpose to collect the leaves? Sometimes I just see a leaf or two in there while i also have a leaf or two in the corner of my pool that never wants to actually flow into the skimmer.

    4. If chemistry is good and I stay on top of things, what's the reason for "turning over the pool". Some say once per day, some say twice. Is the main reason to just keep water moving to prevent algae on walls, or should it not matter as much if levels are correct and the pool is closed often?

    I know, a lot of variables. I'm thinking of doing some experiments today by making my own PVC returns for doing a "true test" of GPM at the various pump speeds to get a better handle on my real flow rates.
    I believe the best guess I have gotten so far is from noting the RPM to trigger the minimum flow rates on the heater and the SWG. Seems like 2000-2100 RPM = about 40 GPM for me.

    Appreciate any comments.
    18x40 - 22,600 Gallon, In Ground Vinyl built 2016. IC-40 SWG, Pentair VS pump, autocover.

  2. Back To Top    #2
    Mod Squad Jimrahbe's Avatar
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    Re: A few random thoughts

    dd,

    The idea that you have to have x turnovers per day is a myth. It is not a requirement to have a clean and clear pool.

    GPM is really not something the average pool owner needs to worry about.

    Here is my standard answer about pump run times...

    Each pool is a little different... You generally run a pump for three reasons:

    1. To keep surface debris moving and being pushed into the skimmers. The more debris the more often you need to run the pump.

    2. If you have a Salt Water Chlorine Generator (SWCG) you'll need to run it long enough to generate the amount of chlorine needed.

    3. To circulate the water to ensure the chlorine is effectively distributed throughout the pool. Two or three hours per day is all that is needed for this to happen in most pools.

    There really is no one answer that fits everyone.

    One of the great things about a variable speed pump is the very low cost to run them. For reference, I can run my pump 24/7 for less than $20 per month.

    Personally, I like the idea of running the SWCG at a low percent of output and running the pump longer. I believe that this allows a more consistent chlorine level in the pool.
    But, we have several members here with the opposite view.. They like to run their pump for as few hours as possible and run their SWCGs at the top end of chlorine production.
    I see no reason to run the pump RPM lower than what the SWCG needs to close the flow switch. For me, most of the time my pump runs at 1,200 where it circulates water and makes chlorine.

    The skimmers main job is to skim or clean the top layer of water, where all the floating junk is. They are also part of the circulation system.

    Thanks for posting,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Caldera Spa.

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    Re: A few random thoughts

    Hi,
    Thanks for the feedback. You confirmed several of my thoughts.

    Today I made some PVC up-spouts and did trials at various pump speeds to determine my GPM.

    I found out the following GPM per RPM for my Intelliflo pump and the corresponding wattages.

    RPM GPM Watts
    500 0.0
    600 0.0 45
    700 1.7 36
    800 2.8 40
    900 3.2 47
    1000 3.8 51
    1100 4.3 57
    1200 5.0 72
    1300 6.0 88
    1400 7.5 110
    1500 7.5 131
    1600 7.2 165
    1700 7.0 212
    1800 10.0 264
    1900 16.7 331
    2000 25.0 394
    2100 28.0 459
    2200 31.9 531
    2300 34.0 610
    2400 36.4 694
    2500 53.0 788
    2600 41.7 888
    2700 44.9 996
    2800 48.8 1109
    2900 51.3 1235
    3000 60.0 1366
    3100 63.2 1507
    3200 66.7 1665
    3300 1822
    3400 1990

    My thought is to run at 3,000 RPM for 2 hours daily,
    2,000 RPM for heat and SWG for 10 hours.
    Off for the remaining 12 hours.

    Or, maybe just go 2,000 or so 24/7 then manually clean on weekends.
    18x40 - 22,600 Gallon, In Ground Vinyl built 2016. IC-40 SWG, Pentair VS pump, autocover.

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    chiefwej's Avatar
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    Re: A few random thoughts

    Why are you ever running the pump at 3,000 rpm? Filtration is better at lower flows and the cost of running the pump goes up exponentially as you increase the speed. I use 1200 or 1400 when running my SWG. I do increase the speed when using solar heat panels on my roof or cleaning with my infloor system, but even then never exceed 2500. Other than that my pump runs at 1000 rpm.

    If you have no solar or cleaning system to support, run the lowest speed that will reliability operate the flow switch in the SWG. Maybe add 200 more rpm for safety.
    chiefwej
    Tucson, AZ
    16x36 rectangular (19k) Pebble Tec play pool/spa, Pentair Intelliflo VS 011018, Super II 2hp (spa), Aqua Rite T-15 SWG, Pro Grid 60 DE, H400 & Heliocol Solar, Dolphin S-300, fill water w/high CH and TA, 50 ppm borates,TF-100 test kit, Smart Home/Alexa pool control

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    Re: A few random thoughts

    Quote Originally Posted by chiefwej View Post
    Why are you ever running the pump at 3,000 rpm? Filtration is better at lower flows and the cost of running the pump goes up exponentially as you increase the speed. I use 1200 or 1400 when running my SWG. I do increase the speed when using solar heat panels on my roof or cleaning with my infloor system, but even then never exceed 2500. Other than that my pump runs at 1000 rpm.

    If you have no solar or cleaning system to support, run the lowest speed that will reliability operate the flow switch in the SWG. Maybe add 200 more rpm for safety.
    Oh, I guess the whole idea of running high comes from my PB who suggested that you run it high to stir things up. (paraphrasing). Get good velocity to... I don't know.. shake stuff of the walls or get stuff to the skimmers better?
    Not sure.
    18x40 - 22,600 Gallon, In Ground Vinyl built 2016. IC-40 SWG, Pentair VS pump, autocover.

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    Re: A few random thoughts

    You get stuff off the walls and floor by brushing. Higher flow rates have nothing to do with that. The beauty of the VS pump is that you can adjust the speed to the most economic and effective for the task at hand. If you are chlorinating, just enough to operate the SWG (add a couple hundred rpm just for safety). For filtration slow rates are fine, but if your skimmer doesn't work at the low rpm you may need to increase it for a short time each day for that.
    chiefwej
    Tucson, AZ
    16x36 rectangular (19k) Pebble Tec play pool/spa, Pentair Intelliflo VS 011018, Super II 2hp (spa), Aqua Rite T-15 SWG, Pro Grid 60 DE, H400 & Heliocol Solar, Dolphin S-300, fill water w/high CH and TA, 50 ppm borates,TF-100 test kit, Smart Home/Alexa pool control

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    Re: A few random thoughts

    With the autocover, I don't have much issue with stuff floating on the top of my pool where skimmers even matter that much.

    The VS pump is nice. I'm forecasting my expected pump cost for the year and it's not very much compared to a single speed pump.
    I am a frequent brusher of my pool (so far) so I think keeping things at a low speed will be fine as long as my SWG and heater are happy.
    18x40 - 22,600 Gallon, In Ground Vinyl built 2016. IC-40 SWG, Pentair VS pump, autocover.

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