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Thread: What is the problem with short runtime?

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    What is the problem with short runtime?

    In pool school the recommendation is to run the swg at least 8 hours a day.

    The problem is the high electricity rates in my area. The intellichlor power center uses 220 watts. At 8 hours and 0.4/kwh, it would cost $0.7 a day or $21 a month in electricity. Bleach is much cheaper in that case.

    I have a 20k pool and by my calculation my chlorine drops by 1ppm a day. At 100% I can run the ic40 for 2.5 hrs or the ic60 at 1.5 hrs to get the chlorine I need. What's the likely problem If I get the ic60 and run it at 50% for 3 hrs a day?

    18'x40' (est. 20K gal) Kidney shape pool // Pentair Intelliflo VS-AU // Pentair Suntouch // Raypak RP2100 Digital // 48sqft DE filter // Stenner 85MHP17 peristaltic pump // Dolphin Deluxe 4.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: What is the problem with short runtime?

    Running for less than 8 hours a day is fine as long as your SWG can keep up with the chlorine demand in the shorter time period. Those instructions date back to the time when everyone was getting undersized SWGs and needed to be aware that pump run time was a big issues with the smaller units sold back then.
    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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    Join Date
    Jun 2009
    Pasadena, MD

    Re: What is the problem with short runtime?

    Your SWCG only draws the full 220W when it is generating chlorine. When you run it at 50%, it's running for half the time, so it's not using the full power draw when the cell is resting. So over the course of an hour, the cell is producing chlorine and drawing full power for 30 minutes.

    3 hours a day might work for generating chlorine, but what about filtration?

    My suggestion is to figure out the pump run time such that your water gets turned over at LEAST 1 to 1.5 times in a 24 hour period, based on GPM rating and set your pump timer for that. This will get you proper filtration. THEN dial down the SWCG until you get the chlorine level to hold where you want it.

    Example: If you are able to produce enough chlorine at 100% in 2.5 hours, then you could run it for 10 hours at 25%, and that would produce the same amount of chlorine as well as get your water filtered properly.
    Doug in Pasadena, MD
    21000 gallons
    Aquapure SWCG system
    Pool owner since 2007

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