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Thread: Longer run time vs higher percentage?

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    JamieP's Avatar
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    Longer run time vs higher percentage?

    Is there any common wisdom on whether it is better to run the SWG at a higher percentage for shorter time, or to run the pump longer with a lower SWG percentage? I would think there would be a cost benefit one way or another in comparing electric rates to the longevity of the salt cell when run at different percentages.

    Right now I am running the pump for about 8 hours with the SWG set at 60% to target an FC of 6. I have the pump set at 1200 for three different windows of run time. If I notice that I've reached my FC target in the evening when I test but there still more run time left on the pump, I just turn it off for the remainder of the last pump run until it comes back on in the morning. Our electric rates are pretty good: $0.069/kWh.

    Would I be better off running the pump longer during the day and lowering the cell percentage? I'd like to maximize cell life, but don't know what affects that the most.

    Thanks for any insight you can give.
    28,000 gallon freeform, Stonescapes Tropics Blue Minipebble with abalone, 3.5' to 8.5' depth. 2 skimmers, 5 returns, dedicated vacuum port, Dolphin Z5 robot. All Pentair equip: EasyTouch 8, IC60 SWG, VS pump, 520 Cartridge Filter, 3 Intellibrites, 2 Color Cascade Bubblers. TurboTwister Slide and 8' Salt System Jump Board. TF-100. My Jan-Mar 2016 build:
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    Re: Longer run time vs higher percentage?

    I think that cell life is related to amp-hours which is amps times time. So should not affect the life of the cell one way or another. For my pool, I have solar heating so I want the pump to rune during daylight hours. Your system may vary.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    mas985's Avatar
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    Re: Longer run time vs higher percentage?

    It won't affect cell life but it will affect pump energy use. So if you can, increase percentage and run for a shorter period of time. You probably don't need 9 hours of run time anyway.
    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: Longer run time vs higher percentage?

    The cell is designed to make xxx amount of chlorine in its life span. A high % with short run times will not extend the life of the cell compared to a low % output with a longer pump run time.

    Your electric rates are low so there will not be a big savings by switching to a shorter pump time vs a long pump time.

    Your pump run time should be controlled by how long it needs to keep the pool clean to your satisfaction. If the short run time with high % output on the SWG works, that will save the most amount of money on electrical costs.

    The question is dialing in the speed and run times of the pump that maximizes your savings. Each pool is different and you will need to experiment with that.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
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    JamieP's Avatar
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    Re: Longer run time vs higher percentage?

    Quote Originally Posted by mas985 View Post
    It won't affect cell life but it will affect pump energy use. So if you can, increase percentage and run for a shorter period of time. You probably don't need 9 hours of run time anyway.
    Thanks Mark. I just edited my post because I realized that my run times only add up to 8 hours. But you're right... I could probably get by with fewer hours.

    So am I understanding it right that the cell life is dependent on how long the SWG is running, not at what percentage it is set at during that time?

    - - - Updated - - -

    Quote Originally Posted by ping View Post
    The cell is designed to make xxx amount of chlorine in its life span. A high % with short run times will not extend the life of the cell compared to a low % output with a longer pump run time.

    Your electric rates are low so there will not be a big savings by switching to a shorter pump time vs a long pump time.

    Your pump run time should be controlled by how long it needs to keep the pool clean to your satisfaction. If the short run time with high % output on the SWG works, that will save the most amount of money on electrical costs.

    The question is dialing in the speed and run times of the pump that maximizes your savings. Each pool is different and you will need to experiment with that.
    Thanks ping. This is a great summary of exactly what I was wanting to know.
    28,000 gallon freeform, Stonescapes Tropics Blue Minipebble with abalone, 3.5' to 8.5' depth. 2 skimmers, 5 returns, dedicated vacuum port, Dolphin Z5 robot. All Pentair equip: EasyTouch 8, IC60 SWG, VS pump, 520 Cartridge Filter, 3 Intellibrites, 2 Color Cascade Bubblers. TurboTwister Slide and 8' Salt System Jump Board. TF-100. My Jan-Mar 2016 build:
    Waxahachie, TX Owner Build - A race to beat the baby!!

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    Re: Longer run time vs higher percentage?

    The cell life is determined by its on time while it's producing chlorine.

    If the SWG is set to 100% and runs for four hours it will be the exact same as 50% for 8 hours of time.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
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    Re: Longer run time vs higher percentage?

    I like to run my pump about 8 hours to keep the surface of my pool skimmed (we're surrounded by trees with lots of pollen). Since it runs longer my SWG doesn't need to be set over 10-20% of the time. If I ran the pump less I would just increase my percentage.....but then my pool surface would have schmutz.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Re: Longer run time vs higher percentage?

    Quote Originally Posted by YippeeSkippy View Post
    I like to run my pump about 8 hours to keep the surface of my pool skimmed (we're surrounded by trees with lots of pollen). Since it runs longer my SWG doesn't need to be set over 10-20% of the time. If I ran the pump less I would just increase my percentage.....but then my pool surface would have schmutz.
    Is your 10-20% just this time of year, or do you have to increase it as the temperature goes up? What is you pool temp now?? What do you try to keep your FC at? Also, what is your CYA? I'm still trying to dial mine in. Thanks!!!
    Mark
    20'x28' IG, Vinyl, (Sept 2015) 14,900 Gallon, 3'4 to 5'6 deep, SPLAPOOL 1.5 HP, 220v, 2 speed pump, Waterway Carefree 27" 400 LB Sand filter, Digital Nano plus SWG, TF-100 test kit /speed stir. Dolphin Primal x3 robotic cleaner

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    Mod Squad YippeeSkippy's Avatar
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    Re: Longer run time vs higher percentage?

    My water has been around 80 degrees. I have an autocover so my pool gets protection from the sun when closed, although it is open a lot of the time too.
    My FC is in the 7 range, my CYA is 60. I keep my CYA a tad lower than recommended again because of the autocover.

    The absolute most I've run my SWG is 30%, but if I'm not on top of it the FC will get too high.

    I always use bleach when I want to spike it up fast.
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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    Re: Longer run time vs higher percentage?

    My water is down to 66 from 77 last week. My SWG adjusts to water temperature changes. I'm running at 30% for 6 hours. FC is 7 and CYA is 70. I don't have a cover, and pool never sees 1 minute of shade except for clouds.
    Mark
    20'x28' IG, Vinyl, (Sept 2015) 14,900 Gallon, 3'4 to 5'6 deep, SPLAPOOL 1.5 HP, 220v, 2 speed pump, Waterway Carefree 27" 400 LB Sand filter, Digital Nano plus SWG, TF-100 test kit /speed stir. Dolphin Primal x3 robotic cleaner

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    Re: Longer run time vs higher percentage?

    I set up a separate timer to run the SWG independently from the pump timer because I have solar water heating and the SWG ran when the pump ran and I had no control over SWG run time.

    It is wired in such a way that the SWG will only run when the pump is on, so I have the SWG set to 100%, and adjust the run time in the timer to get to the proper chlorine level.
    SWG: CircuPool (May 2014) SI30+Plus; 3000ppm seems ideal;
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    Re: Longer run time vs higher percentage?

    I leave mine set at 40% and run my pump from 7am to Midnight (30% between 7am-11am, 60% from 11am to 7pm, 30% from 7pm to 12am). I keep my CYA lower than recommended (about 40), but my chlorine levels pretty much stay between 4-5.5 every time I check.

    Last year, my water stayed balanced all year without me having to add anything after May. So far, it has stayed balanced this year after the initial SLAM was finished after opening and I balance it (although it's only been since last Friday).

    I know I probably run it more than most, but it doesn't seem to affect my electric rates. I put in new HVAC units at the same time as I put in my pool, and my Summer rates went down about $150/month even with the pool added.
    In Ground 14 x 28 vinyl liner; 11,600 gallons; Hayward EcoStar VSP; SWCG - Hayward T Cell 15.

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    Re: Longer run time vs higher percentage?

    Quote Originally Posted by mas985 View Post
    It won't affect cell life but it will affect pump energy use. So if you can, increase percentage and run for a shorter period of time. You probably don't need 9 hours of run time anyway.
    Unless you can run the pump on really low speeds at a more efficient rate - go back to my calculations I was working on.
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    mas985's Avatar
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    Re: Longer run time vs higher percentage?

    I would assume the pump speed would be the same in both cases (why wouldn't it) so it is only run time that matters.
    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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