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Thread: SWG, chlorine demand and a hot summer

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    SWG, chlorine demand and a hot summer

    PH7.5
    TA 70
    CYA 70
    CH150
    Salt 3450 (does not change over weeks), should it be using more salt?

    Pool looks wonderful, no issues at all.

    I have been monitoring my TC using a log, looking at the demand of the chlorine loss from day to day, I test usually mid day.

    I have the SWG @ 75% and supplement bleach as needed, I lose around 1-4 PPM per day, mostly 2ppm depending on rain, sun, heat.

    Q- should I be going through more salt? I cleaned the SWG 2 weeks ago with acid, or would this chlorine demand be typical? It makes me question the value of the SWG.. It seems prior to heat of summer the SWG was producing positive amounts of chlorine, now it doesn't keep up, was at 50% until 2 weeks ago. I let it get down to 5PPM and then dump 121OZ in which bumps up to 12PPM, so use 121OZ or so a week, typically bump up for weekend when bathing load is higher.

    Would like to hear from others
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Re: SWG, chlorine demand and a hot summer

    How old is the cell. Acid cleaning is hard on them but some times necessary. How long do you run the pump. When using SWG and you need more clorine it is better to run the pump longer then turn the swg up.

    IG, pebble tech, 25K gallons, grotto, SPA that spills into pool, water slide, two other water falls. Equipment Pentair, filter FNS + 60, pool pump 1.5HP single speed wisperflo, spa 3 HP single speed wisperflo, grotto/ slide 3HP single speed wisperflo, waterfall 2HP single speed wisperflo, minimax NT 400K btu, Hayward XL pool vac, SWG IC60, compool 3800 automation, built 2007.

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    Re: SWG, chlorine demand and a hot summer

    Quote Originally Posted by bacr619 View Post
    How old is the cell. Acid cleaning is hard on them but some times necessary. How long do you run the pump. When using SWG and you need more clorine it is better to run the pump longer then turn the swg up.

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    3rd Pool season, We installed June 2013, it ran 12 hours a day until we covered it September of 2014, opened May 2015--- runs 12 hours a day 8am-8pm
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Mod Squad YippeeSkippy's Avatar
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    Re: SWG, chlorine demand and a hot summer

    I don't understand your question about salt. The SWG doesn't "use up" the salt and require replenishing often. It actually breaks down the salt to release chlorine, then it becomes bound together once again in the pool as just "salt" ready to start the cycle again. Cool, huh?

    Unless you've replaced water or diluted it somehow (rain, overflows, backwashing) since taking that reading your salt number looks okay to me, but what does your SWG manual list as the optimum salt level?

    Is your SWG too small for your pool? TFP suggests using one that is 1.5-3x the size of your pool to allow for lower demand on the hours they'll produce.
    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: SWG, chlorine demand and a hot summer

    That is pretty cool! Didn't know about the salt.

    I don't know what the SWG is rated for I will look it up, our pool isn't large at 11500g
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Divin Dave's Avatar
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    Re: SWG, chlorine demand and a hot summer

    its correct about the amount of salt. It doesn't get used up, and as long as the salt is adequate enough for cell to make chlorine it will and be capable of its the rated amount of chlorine.

    I would also ask how large the cell is rated for. TF recommends cell that is 1.5 - 3 times larger than the pool volume.
    So for your pool, a 25K cell would be a good recommendation.

    Also, depending on how much shade or not your pool gets will play some role on how much FC gets burned off by UV which also effect the output the SWG needs to replace it.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
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    Re: SWG, chlorine demand and a hot summer

    I'm curious about the chemistry involved here. The chlorine presumably comes from the NaCl molecules, in a chemical reaction driven by the energy from the cell. As such, would not the salt be consumed? Does the chlorine not gas off? If so, where does the Na go? By what means does the Cl become recombined with the Na to avoid salt loss?
    Lagoon 40x22, Vinyl, 27,000 gal, 1HP WhisperFlo Pump, Pentair 60 gpm Sand filter, Hayward Brominator (used for chlorine pucks only when away), Rheem gas heater, Dolphin M4 Robot
    Waterfall on separate dedicated pump

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    Re: SWG, chlorine demand and a hot summer

    Quote Originally Posted by Divin Dave View Post
    its correct about the amount of salt. It doesn't get used up, and as long as the salt is adequate enough for cell to make chlorine it will and be capable of its the rated amount of chlorine.

    I would also ask how large the cell is rated for. TF recommends cell that is 1.5 - 3 times larger than the pool volume.
    So for your pool, a 25K cell would be a good recommendation.

    Also, depending on how much shade or not your pool gets will play some role on how much FC gets burned off by UV which also effect the output the SWG needs to replace it.
    Pentair IC20, so rated for 20K pool, would someone; 1. run it longer to produce more chlorine 2. increase output 3. use bleach to supplement 4. run on superchlro for 24 hours

    I don't think there is one correct answer curious to hear from people with more knowledge

    its close to 11AM, pool has sun on about 30%, around noon will have full until nearly 7PM
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Mod Squad YippeeSkippy's Avatar
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    Re: SWG, chlorine demand and a hot summer

    Quote Originally Posted by WWells View Post
    Pentair IC20, so rated for 20K pool, would someone; 1. run it longer to produce more chlorine 2. increase output 3. use bleach to supplement 4. run on superchlro for 24 hours

    I don't think there is one correct answer curious to hear from people with more knowledge

    its close to 11AM, pool has sun on about 30%, around noon will have full until nearly 7PM
    -Running it longer versus increasing its output for a shorter time seem to be a wash to me. About the same draw on the unit.
    -I always use bleach to supplement when I want *instant* rise in chlorine, for whatever reason. I know the cell is not going to give me *instant* protection like the liquid chlorine will.
    -I avoid running superchlorinate because that seems to me to be a lot to ask of the cell. I'm trying to limit the wear and tear on my cell to make it last as long as possible. It is my Ace in the pocket for maintaining the low steady chlorine level in my pool.
    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: SWG, chlorine demand and a hot summer

    Well turns out I had algae that wasn't visible until the FC got down to 5PPM or so, turned off the SWG and did SLAM until all conditions were met and let the FC drift down, at 11PPM I turned the SGW back on at 100%, 24 hours later it was 13PPM, turned down to 75% and after 24 hours was still at 13PPM

    I guess I will leave it at 75% until I see a swing up/down
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Re: SWG, chlorine demand and a hot summer

    For CYA=70, the recommended FC target is 5.

    From what I have read here I think your cell has to work more to maintain your current level, and that in turn will apparently reduce the life span of the cell.
    23,000 gallons IG gunite, pebble (I think)
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    Polaris pool cleaner (with booster pump)
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    Re: SWG, chlorine demand and a hot summer

    Thanks, I was thinking about that this morning, however at 5 it seems so close to potential "disaster", I think I will turn off the SWG after the weekend and let it drift down close to 5
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Re: SWG, chlorine demand and a hot summer

    Quote Originally Posted by Sparkle View Post
    For CYA=70, the recommended FC target is 5.

    From what I have read here I think your cell has to work more to maintain your current level, and that in turn will apparently reduce the life span of the cell.
    Thinking about this, I don't think it is doing more work as it is just putting out a certain amount of chlorine per cycle, at its current setting its just maintaining at 13PPM, would be no different if it was at 5PPM

    Right?

    today have FC15.5PPM up from 13 24 hours ago, reduced SWG output to 50%
    Tallman Monterey (fiberglass), 16'x33', 11500 gallons, 480 sq/ft, Depth: 3' - 5' 6", Salt Water, TF-100, Pentair pump, sand filter, Easy Touch Control System, SWG

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    Re: SWG, chlorine demand and a hot summer

    Chlorine loss is a percentage, not an absolute value. So at 13 PPM you lose almost three times as much as you do at 5 PPM.

    So your SWG has to work almost three times as long to maintain a level of 13.
    23,000 gallons IG gunite, pebble (I think)
    Hayward SP2610X15 1.5 HP Pump, Hayward sand filter
    Mineral Springs SWCG (it's actually Hayward/Goldline), Hayward Goldline T-CELL-15
    Polaris pool cleaner (with booster pump)
    TF-100, SpeedStir, K-1766 Taylor Salt Test, Lamotte Borate test strips

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