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Thread: Chlorine keeps dropping

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    Chlorine keeps dropping

    Hello again,

    On another thread, I had asked about pH, and as the discussion went on, I was told to get my Cl up to 8. I got it up to 11.5, last weekend, and it has been steadily dropping over the last week. I performed a drop test last night and got 3.5, this morning it was 3.0
    The other test results from my TF100 (if no user error was involved) were:
    TA 80
    CYA 50
    pH 7.8 - (it has been a day or two since I added acid, which I did this morning)

    Looking at the chart for SWG, it looks like if I just raise my CYA to 60, my Cl may be OK. I am curious of why it dropped so quickly over the last week. I run my SWG 12 hours a day.

    Is there anything to worry about?
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    YOur SWG is not keeping up with the consumption.

    I would do an overnight FC loss test (see pool school) to determine if you have organics in your pool.

    If you pass that test, you'll simply need to increase your SWG output. If you fail, you'll need to shock.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Chlorine keeps dropping

    I understand that it is consumable, but I did not expect at such a great rate when my SWG was running every day. That too is expected?
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    My apologies. I didn't see your swg the first time I posted. I have edited (changed) my reply.

    EDIT AGAIN!!:: I think I woke up too early this AM. I also overlooked that you have apparently done the overnight FC loss test already and passed. About all that's remaining then, is to up your percentage on the SWG or run time on the pump.

    Sorry it's taken three tries to get you a reasonable answer.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Richard320's Avatar
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    Re: Chlorine keeps dropping

    Don't forget to turn the SWG off when doing the overnight test!
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: Chlorine keeps dropping

    Was the SWG off when you lost the .5 overnight?
    Are you certain the SWG is functioning properly?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Chlorine keeps dropping

    Yes, I did have the SWG off when I took the reading last night in the dark.

    The sun was up for an hour or so before I got the reading this morning, not direct, but the pool was getting sunlight.

    The SWG was off until after I took my morning reading. It sounds like I am not too far off base, I need to increase my percentage is how I reading these replies.

    I am not convinced on how to know if my SWG is functioning properly, I don't see any warning lights of any kind, and the pool store is close on my salt levels. I see the cell on/off light change. Is there a good way to verify it is working properly?

    Thanks for all of your guidance!
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    frustratedpoolmom's Avatar
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    Re: Chlorine keeps dropping

    An overnight loss of .5 with the SWG off is very good
    What percentage is it on now? Increasing your CYA and upping the % may help, if you are sure it's not a malfunction issue. When is the last time you cleaned the cell?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Chlorine keeps dropping

    OK, maybe I have no worries here, it is a new SWG, and the gauge does indicate it is ready for cleaning.

    I don't have a good frame of reference on these things
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    If you recently started your SWG for the season and FC was at 0 and you CYA is lower than recommended, then your SWG may not be able to generate FC quickly enough to keep up with demand. Bump your CYA up to 70 and use liquid chlorine to get FC to the recommended level. Set the output on the SWG on the % recommend by the manufacture and see if it is able to keep up.
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Re: Chlorine keeps dropping

    You could try taking a water sample as directly from the return jet as possible, it should show the FC of the water coming out of the SWG. If it's higher than the pool in general, then the SWG is working.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Chlorine keeps dropping

    "OK, maybe I have no worries here, it is a new SWG, and the gauge does indicate it is ready for cleaning."

    I suspect the gauge your are talking about is the pressure gauge for the filter. As the pressure increases it is an indication you need to clean your filter but is not related to your SWG cell.

    You should remove your cell and inspect it. My SWG cell gets dirty sometimes and stops generating chlorine even though the numbers on the diagnostic panel look fine. The symptom I see is I cannot seem to keep chlorine in the pool. What happens is you get a build up of white goey "funk" between the plates and the current that is supposed to be generating chlorine ends up being shorted across the goo.

    Try this:
    - Remove cell and rinse it out with a hose.
    - Grab a flashlight and the cell and head somewhere out of the sun ( I use my shed) where there is limited light. Being in a dimly lit location is very important.
    - While looking into the cell, shine the flashlight from the other end and look at the spaces between the plates inside the from top to bottom. Rotate the cell 180 degress (to change your viewing angle). Flip the cell around to and view from the other end and repeat.
    - If you see any goo it must be removed. I have found spraying with a hose is not enough and you need to give it a little help. I use a nylon cable tie of a piece of trimmer string to dislodge the buildup from between the plates. Don't use anything metal that can damage the plates. Once you break it loose the hose can be used to flush it out.

    Hope this helps,
    In ground 15 X 33 10,400 gal. Fiberglass
    Two Returns, Two main drains, One skimmer
    Aqua Logic SWG, Hayward TriStar 1.5HP
    Hayward C3025 (325 sq /ft) Cartirdge Filter
    Solar Heater (Details at http://www.bakerlabs.com/solar)

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    Re: Chlorine keeps dropping

    Quote Originally Posted by PaulR
    You could try taking a water sample as directly from the return jet as possible, it should show the FC of the water coming out of the SWG. If it's higher than the pool in general, then the SWG is working.
    --paulr
    I gave this a try today, I did not see any difference.
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    Um, did the SWG appear to be on at the time? If it wasn't on, it wouldn't be producing... should've made that clear originally, hope you figured that out on your own... but if it looked like it was on, then it seems probable there's an issue with the unit.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  15. Back To Top    #15

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    Re: Chlorine keeps dropping

    Quote Originally Posted by PaulR
    Um, did the SWG appear to be on at the time? If it wasn't on, it wouldn't be producing... should've made that clear originally, hope you figured that out on your own... but if it looked like it was on, then it seems probable there's an issue with the unit.
    --paulr
    LOL, I knew enough to check that out. It is really hot here, based on what I have read about SWG, what value might I have expected on the return? What is an "average" percentage to have my SWG on? Currently, it is at 60%, I am sure I need more stabilizer as well.

    I would like to try whatever I have to before I try PVille's suggestion.
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    We have about reached the limit of my understanding of SWGs (didn't take long, did it...) I didn't see a CH number, but based on the other numbers it seems unlikely you'd be getting calcium scaling inside the cell.

    Tweaking up the CYA should help. The FC will have to be higher in proportion, but it should be easier to maintain.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

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    Re: Chlorine keeps dropping

    Understood, my CH is 300, I am hoping upping the CYA will show some benefit.
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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    Re: Chlorine keeps dropping

    I have to thank all who helped me here on this post! Turns out, I should have verified the obvious first, I had a Jandy Aquapure 700 installed which will only service up to about 15,000 gallons. My pool is roughly twice that size, and I was only running the SWG for 12 hours. DOH!

    I don't have to be chem geek to do the calculations on this one I post this in case some other new owner stumbles across this post wondering why their SWG isn't getting the job done.

    Lucky for me a service light came on or I might not have done the research. My pool company realized the error of their installer, when I told him my model number and (very) promptly replaced the unit even though he had to drive from Atlanta (why they didn't catch it on site).

    I wish I could call them out by name, but don't want to get in trouble .

    If it hadn't been for all the help here, I would have been swimming in algae all summer!!

    Maybe now, I won't be buying (as much) bleach!
    Inground 30,000 gallon Pebble-Sheen pool
    Jandy Aqua-Pure 1400 Cartridge filter

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