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Thread: Salt pool - Low Chlorine Levels

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    Salt pool - Low Chlorine Levels

    The initial salt pour was about 4 months ago and the pool is 5 months old. 26,500 gallons. The chlorine levels keep dropping to near nothing. I've turned the SWG system dial up from 50% to 60, then 70, then 80. I get higher chlorine levels for a few days, then it drops to nothing again. Do I need to add more salt? The SWG level shows a consistent 3300-3400.
    36 x 16 IG, SWG, FAFCO Solar Heating System, WetEdge Primera Stone Sky Blue Treasure, 8.5' - 3.5' depth, 6' S.R. Smith Flyte-Deck II Dive Stand, Interfab X-Stream slide, 27k gallons, doggy tanning ledge w/ 2 bubblers, 2.75 Hayward Tristar pump, Hayward 425 cart filter, Hayward T-15 Salt Cell, Hayward ColorLogic 4.0 light, Dolphin Z5

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    Re: Salt pool - Low Chlorine Levels

    Others will chime in but I think your salt level is just fine. You may need to increase your pump run time. They say it's better to increase the pump run time and turn down the SWG a bit so that the cell will last longer
    15,000 gallon free form Viking fiberglass pool. Hayward Star-Clear Plus C12002 cartridge filter. Hayward Swim Pure Plus T-15 SWG. Testing with TF-100 Kit. 2 speed 1.5HP Supreme pump. Dolphin Nautilus robotic cleaner

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    JoyfulNoise's Avatar
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    Re: Salt pool - Low Chlorine Levels

    What are your water temperatures? Most of the SWG's have a cold water cutoff and stop producing chlorine when the water temp is below 58F. It could be that your water is warming up slightly during the day and your cell is only able to generate chlorine when the water warms. Most people that live with "year-round" pools switch to manual chlorination in the winter months.

    However, because it is also cold, your chlorine loss rate should be very minimal. I only lose maybe 0.1-0.2ppm FC per day. If your FC is at target levels and then drops to 0ppm in less than a day, then you might also have an algae problem. You can test that by doing an overnight chlorine loss test (OCLT) - Pool School - Perform the Overnight FC Loss Test (OCLT)
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Re: Salt pool - Low Chlorine Levels

    Can you provide us with some test results please? You could possibly have an algae issue.
    11 000 gallons, IG, Fibreglass, Monarch Sand Filter, Davey Typhoon C100M 1HP pump, Davey Chloromatic Mc16CTO ESR SWG, Davey Pool Wall Climba Robot, Daisy Solar Cover,
    K-2006

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    Re: Salt pool - Low Chlorine Levels

    +1 on the cold water. Mine stops acting right a little below 70. I turn mine off and switch to bleach. I test weekly and keep FC at 10ish.
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Salt pool - Low Chlorine Levels

    I had a similar situation earlier in fall, and it turned out to be an algae bloom in my light niche. SWG was doing fine, but the chlorine was being used up by algae. Just another possibility, been there, done that. SLAMmed it, all went back to good levels. Now I'm not producing CH due to water temps being low, but I can wait that one out.
    Phil
    ~9600 gal gunite pool, NEW July 2015; Pentair Intelliflo 2 VST pump; Pentair C&C 150 filter; Pentair Intelliclor IC40 swg; solar heat w/ Pentair Solartouch controller, screened. Taylor K 2005 test kit, FAS-DPD separate test, Taylor K1766 salt test

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    Re: Salt pool - Low Chlorine Levels

    Quote Originally Posted by JoyfulNoise View Post
    What are your water temperatures? Most of the SWG's have a cold water cutoff and stop producing chlorine when the water temp is below 58F. It could be that your water is warming up slightly during the day and your cell is only able to generate chlorine when the water warms. Most people that live with "year-round" pools switch to manual chlorination in the winter months.

    However, because it is also cold, your chlorine loss rate should be very minimal. I only lose maybe 0.1-0.2ppm FC per day. If your FC is at target levels and then drops to 0ppm in less than a day, then you might also have an algae problem. You can test that by doing an overnight chlorine loss test (OCLT) - Pool School - Perform the Overnight FC Loss Test (OCLT)
    Quote Originally Posted by pooldv View Post
    +1 on the cold water. Mine stops acting right a little below 70. I turn mine off and switch to bleach. I test weekly and keep FC at 10ish.
    Thanks, that's probably it. My water temp is between 50-60 most days. I didn't realize the SWG stopped producing chlorine at a certain temp. Can you adjust the temp threshold?

    I really don't want to go back to dumping bleach in the pool every other day.
    36 x 16 IG, SWG, FAFCO Solar Heating System, WetEdge Primera Stone Sky Blue Treasure, 8.5' - 3.5' depth, 6' S.R. Smith Flyte-Deck II Dive Stand, Interfab X-Stream slide, 27k gallons, doggy tanning ledge w/ 2 bubblers, 2.75 Hayward Tristar pump, Hayward 425 cart filter, Hayward T-15 Salt Cell, Hayward ColorLogic 4.0 light, Dolphin Z5

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    JoyfulNoise's Avatar
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    Salt pool - Low Chlorine Levels

    Quote Originally Posted by tedujam View Post
    Thanks, that's probably it. My water temp is between 50-60 most days. I didn't realize the SWG stopped producing chlorine at a certain temp. Can you adjust the temp threshold?

    I really don't want to go back to dumping bleach in the pool every other day.
    Sadly, no. The purpose of that cutoff is to protect your cell. Electrolytic chlorine production is temperature sensitive. As the water temp drops, the efficiency of the chlorine production falls off and you can actually damage your cell if you try to run it with cold water.

    Most people just manually chlorinate in the winter because your daily FC loss should be very low. If you are experiencing an excessive chlorine demand in the winter, then you may have an algae problem (yes algae does grow in cold water, just very slowly).

    For example, I have manually added bleach three times to my pool since the SWG stopped running in late November.


    Last edited by JoyfulNoise; 01-21-2016 at 05:03 PM. Reason: Checked notes, added bleach three times not twice
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Mod Squad pooldv's Avatar
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    Re: Salt pool - Low Chlorine Levels

    I test once a month or so and usually add a gallon or two. I try to get FC back above 10ish. I have also probably added 3 times since shutting off the swg.
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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