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Thread: Add chlorine if water temp under 55F

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    Add chlorine if water temp under 55F

    Hi,

    I'm getting old. I can't remember what I've read here (and can't find now!)

    If temp gets below 55F and bacteria not active do I need to maintain a chlorine level?

    Bob
    Thanks As Always!
    Bob

    23,000 gal in-ground, Aquarite salt sys, Intellitouch i7 +3, Hayward cartridge filter (4) C-5025, Polaris 280 Pool Cleaner, 3/4 HP booster pump, Hydrazzo plaster.

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    JasonLion's Avatar
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    Re: Add chlorine if water temp under 55F

    It is very unlikely that algae will grow at temperatures below 55 degrees, but it is possible. If the pool remains open (not covered, pump runs at least once a day) it is best to maintain a chlorine level. At lower temperatures chlorine lasts far longer than it does at higher temperatures, so you will probably only need to add chlorine once every week or two. Note: most SWGs shut down around 50 degrees, so you can't usually depend on a SWG to maintain the FC level over the winter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Mod Squad Bama Rambler's Avatar
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    Re: Add chlorine if water temp under 55F

    I run my Liquidator in the winter just like I do in the summer. The big difference is that I have it set on 1 cc/min right now running my pump in two 3 hour intervals per day, whereas in summer it's usually on about 3 to 4 cc/min running two 4 hour intervals. I keep the FC level about the same all the time.
    Dave J. TFP Moderator
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    Re: Add chlorine if water temp under 55F

    This is my first winter on BBB but I added chlorine on 11/22 and then not again until 12/18. I am moderately suspicious that the inch of rain we got that week was part of why the FC level dropped; it had been holding pretty steady before then (water temp around 50F).
    --paulr
    BBB "Intermediate Swimmer"
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    Re: Add chlorine if water temp under 55F

    Absolutely! Keep your chlorine level at the normal level that it needs to be for your current CYA.

    You will notice that you use very little chlorine when compared to the times of the year when your water is warm. Once my water temp gets to the 50 to 55 degree range, I will only test once a month or so but I do find that I still need to add a little chlorine here and there.

    While it's true that your pool probably won't turn green in January, I guarantee you that organics can and do exist in cold environments. For confirmation of this, see what happens when you leave old food or opened drinks in the refrigerator for a couple of weeks. And refrigerators are much colder than your 50 degree water.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
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    mas985's Avatar
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    Re: Add chlorine if water temp under 55F

    It has been my experience that very little chlorine is needed to keep algae at bay when water temp drops below 50 degrees. Usually, I just let my SWG shut off automatically at low temperatures and do nothing and for the last four years have never had an algae bloom. As Jason pointed out, chlorine can last a number of weeks in cold water. Just monitor the chlorine level and if you don't get a reading, then you might consider adding some extra.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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    Re: Add chlorine if water temp under 55F

    Please remember that algae is not the only thing you don't want in the pool. Hepatitis, West Nile, Legionaires, and many other not nice bugs need to be dealt with.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    mas985's Avatar
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    Re: Add chlorine if water temp under 55F

    Quote Originally Posted by PoolGuyNJ
    Please remember that algae is not the only thing you don't want in the pool. Hepatitis, West Nile, Legionaires, and many other not nice bugs need to be dealt with.

    Scott
    Given that the water is lower than 50 degrees, I certainly won't be swimming nor anyone else I know.

    But serious, when my SWG does shut off, the chlorine barely drops. Also, it takes less chlorine to kill pathogens than it does algae so you normally see algae well before pathogens become a problem.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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    Re: Add chlorine if water temp under 55F

    My water temp is 40, PH and TA are fine, but FC is 0.0. My SWG has not been running much because the temp is too low and has been for several days. I live in NE TN. We occassionally heat up the pool on the weekend to swim but have not the last 2 weekends due to extremely low air temp. I want to get my chlorine up so that we can swim when the air temp gets a little warmer. Should I add bleach or turn on the superchlorinator? Is there another solution?

    Thanks for your help!!

    Dory
    East TN
    13,000 gal San Juan Fiberglass Pool;SWG; GoldLine Pro Logic Controls
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    JasonLion's Avatar
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    Re: Add chlorine if water temp under 55F

    SWGs don't usually work when the water is very cold, so it is normally much simpler to add bleach.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Add chlorine if water temp under 55F

    Thanks for the reply!! How much bleach should I add? My pool is about 13,000 gallons.

    Thanks!!
    Dory
    East TN
    13,000 gal San Juan Fiberglass Pool;SWG; GoldLine Pro Logic Controls
    Hayward Sand Filter; Hayward Max-Flo XL Pump;Polaris 380; Hayward ColorLogic LED
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    polyvue's Avatar
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    Re: Add chlorine if water temp under 55F

    Quote Originally Posted by creechy
    Thanks for the reply!! How much bleach should I add? My pool is about 13,000 gallons.

    Thanks!!
    Dory
    Enter your latest test results into the Pool Calculator (or best guess) and the amount of chlorine you're targeting... in winter, you should be OK with 5% or more of CYA. For example, if the water's CYA is 40 ppm, target 2.0 ppm free chlorine - or above. The calculator will tell you exactly how much liquid chlorine/bleach you need to add.

    http://www.poolcalculator.com/
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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