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Thread: No chlorine registering in my pool

  1. #1
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    No chlorine registering in my pool

    I have an inground vinyl pool that is 45,000 gallons, with a 2 hp Hayward Super Pump, a sand filter that holds 300 lbs of sand, and automatic chlorinator, that we have had since 1989. Since opening it we have been unable to get a chlorine reading when we test the water. We had quite a few of problems with the water clearing up after we opened it, and finally had to use alum to get the junk out. We swept that away through waste, and now the water is sparkling clean, but still no chlorine reading. We have shocked, super chlorinated, adjusted, had the water tested for phosphates (0), and every other problem conceivable. We changed the sand in the filter this spring. The water values as of 15 minutes ago were:

    T/A-120ppm
    F/C-0
    T/C-0
    C/H-220
    CYA-45ppm
    PH-7.5

    I am at my wits end. The pool has been open over a month and while it has been difficult getting it cleared up, we finally managed. However, the no chlorine is really bugging me. We have the chlorine cranked all the way up, the tabs are dissolving, pump is running 24/7, and we are floating clorine tabs in a floating chlorinator. Still nothing. HELP!!
    ctlss: 45,000 gallons vinyl, I/G, 300 lbs sand filter, 2 HP Hayward Super Pump, Polaris 360 automatic pool sweep, 1/2 horse booster pump, 355,000 btu propane heater

  2. #2
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    Re: No chlorine registering in my pool

    Hi and welcome.
    Have you read pool school?

    This type of chlorine demand is normal from the situation you have described.

    You need to read
    Shocking Your Pool

    and continue shocking until the FC holds overnight.

    Your CYA at 45 is almost at the high end of the acceptable range to be using tablets - once you hit 50 it would be a good idea to switch to liquid chlorine for your daily chlorination.

    Hope this helps, post back if you have any questions.
    Helpful links: Pool School; The Pool Calculator; 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
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  3. #3
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    Re: No chlorine registering in my pool

    Thanks, we have shocked the heck out of this pool. And CYA is where the pool experts at my pool store told me to get it to. We didn't have that much in there (about 20ppm) and they told me to add stabilizer to raise the CYA. And we have put so much shock into it, that it isn't funny. Doesn't seem to help, especially since there is no dead chlorine in the pool at all. No free, no total, no chlorine at all! ARGHHH!
    ctlss: 45,000 gallons vinyl, I/G, 300 lbs sand filter, 2 HP Hayward Super Pump, Polaris 360 automatic pool sweep, 1/2 horse booster pump, 355,000 btu propane heater

  4. #4
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    Re: No chlorine registering in my pool

    ctlss,

    All your chlorine is being consumed by sunlight and algae. It is a consumable item...it is not constant.

    There is no such thing as dead chlorine. Once it is consumed either by organics in your pool or sunlight, it simply is non-existant......that's what's happening in your pool.

    Read ABC's of pool water chemistry......that'll get you started.

    Meanwhile, you need more chlorine. I assume your using an SWG so I suggest you plan on using liquid chlorine (as a supplement) once you get this all figured out.
    Dave S.
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    TFTestkits , PoolMath , Pool School

  5. #5
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    Re: No chlorine registering in my pool

    See, the problem is that we have been running this pool since 1989, using the exact same chlorine and chlorinator. We have never had a problem.

    Have never used liquid chlorine and according to my pool people it dissipates more quickly than the tabs (I had already thought of that and was told it is weaker than the shock, and since the shock isn't raising the level, the liquid won't either, more than likely). And there hasn't been any sun, and we have no algae. I have added algaecide, lots of it, and any algae that was there is now gone.

    The water was very turbid, so we added the alum to floc it, and got that cleared up. Had a chemistry pool expert come out and test the water and the only problem that he could find was the chlorine wasn't registering, even after the pool was shocked. Everything else was perfect. So got new test kit, test strips, and new tabs. Still nothing.

    The water is beautiful, sparkling clean, no slime on the sides or steps, and you can smell that pool smell, but nothing! Pool store suggested that I may have a chlorine lock. According to what I can find about that, the symptoms are wrong And I have been doing a lot of reading about the chlorine problem and all the sites reference dead chlorine, as do both my pool store and the pool expert that came out to check it, so I am a bit confused about there being no such thing.
    ctlss: 45,000 gallons vinyl, I/G, 300 lbs sand filter, 2 HP Hayward Super Pump, Polaris 360 automatic pool sweep, 1/2 horse booster pump, 355,000 btu propane heater

  6. #6
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    Re: No chlorine registering in my pool

    Hey,

    Chlorine is consumed by two things.......the Sun and organics in your pool. There is no other cause for chlorine to disappear.

    Put enough liquid chlorine in your pool to raise it to around 6ppm.....that'll be about 4.5 gallons. Test your chlorine in 20-30 minutes and I promise you will have some. It will likely be gone overnight because it is being consumed by what I suspect are invisible organics (algae) in your pool.

    I don't mean this harshly but factually......If your pool store suggests "chlorine lock" as a cause, you should get a new source for advice. Chlorine lock doesn't exist.
    Dave S.
    Site Owner
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    TFTestkits , PoolMath , Pool School

  7. #7
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    Re: No chlorine registering in my pool

    Your water may appear clean now, but it won't be until you shock it until the FC holds overnight. My money is on the fact that you have (in addition to the UV rays from the sun) something in your pool that is consuming it quickly. The tablets are too slow. Stop using them. Switch to bleach or another liquid chlorine source. Use the Pool Calculator (link in my sig) to calculate your dosages and add all the chlorine the Pool Calculator tells you to add.

    You have been given good, credible advice in the previous posts. Please read the prescribed sections and you will be able to control this situation.

    You don't have "chlorine lock". Overstabilized pools still have chlorine. You just don't have enough chlorine at all. Shock your pool using our methods.
    TFP Moderator
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  8. #8
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    Re: No chlorine registering in my pool

    Liquid chlorine adds chlorine to the pool exactly the same as the tablets you use in the chlorinator, except that the tablets also add CYA and lower the PH. Liquid chlorine is nice because it doesn't change your CYA or PH levels. The powdered/granular "shock" products have similar problems, depending on what they actually contain, adding either CYA or CH.

    I suspect that you can't hold an FC level because of ammonia in the water. If there is ammonia, it will wipe out all the chlorine you add very quickly until you finally add enough to burn off the last of the ammonia. It would be interesting if you could get an ammonia test result. Ammonia test kits are inexpensive and nearly any aquarium store should have them.

    As duraleigh said, there is no such thing as "chlorine lock", that is just what pool people call it when they can't explain what is happening.

    There is a procedure you can do, described in this post that will tell you how much chlorine you need to add before you will be able to maintain an FC level above zero.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  9. #9
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    Re: No chlorine registering in my pool

    I will try all your suggestions. The only thing I haven't tried is the chlorine test using the bucket and adding liquid chlorine as the pool people told me not to add it, it would ruin my liner. The chlorine and shock that I buy, SAY that there is no stabilizer, and my ph was perfect until I added the Alum. I adjusted it back to the right levels. I checked the ammonia and nitrates and they were zero. I have all the tests kits for my salt water and regular aquariums. I am off to read the pool chemistry link. Thanks for all the advice, I will try your suggestions and see if it works. As for the chlorine lock, it sounded odd to me, and so I didn't follow any of the recommendation on the numerous web sites, nor from the 3 different pool "experts" that told me this was the problem. We have never had the problem with chlorine that we are having this year. As soon as I do the chlorine test, I will let you know the results. Once again thanks for the info.
    ctlss: 45,000 gallons vinyl, I/G, 300 lbs sand filter, 2 HP Hayward Super Pump, Polaris 360 automatic pool sweep, 1/2 horse booster pump, 355,000 btu propane heater

  10. #10
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    Re: No chlorine registering in my pool

    Hi ctlss,

    You have gotten great advice and folks here will help you restore your pool water chemistry to be safe and beautiful.

    Wallyworld sells the ammonia kit in the pet department. Also, some pet stores will test for ammonia for free.

    Your pool is HUGE and it is going to take a lot of chlorine to bring it back around.
    You might want to check with the local pool stores/big box stores for prices and availability on Liquid Chlorine (10 to 12.5%). Make sure it's fresh!

    If you want to take control of your pool you should order one of the recommended test kits.
    See Test Kits Compared.

    Where are you located? City and State?

    What do you use for your fill water? City/county? Well? Is it expensive?

    Welcome to the forum
    TFP Moderator -TF100 Test Kit - TF100 TestKit YouTube Channel- PoolMath- Pool School -
    You're done SLAMing when: 1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.
    ~Do at least one thing every day that makes you happy.~

  11. #11
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    Re: No chlorine registering in my pool

    The chlorine and shock that I buy, SAY that there is no stabilizer....
    Are you using Lithium Hypochlorite?
    TFP Moderator -TF100 Test Kit - TF100 TestKit YouTube Channel- PoolMath- Pool School -
    You're done SLAMing when: 1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.
    ~Do at least one thing every day that makes you happy.~

  12. #12
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    Re: No chlorine registering in my pool

    Quote Originally Posted by ctlss
    The only thing I haven't tried is the chlorine test using the bucket and adding liquid chlorine as the pool people told me not to add it, it would ruin my liner.
    It will not harm your liner. This is actually a commonly mentioned scare tactic used by some less than reputable pool store employees and is solely designed to frighten you into buying their pricey products and also to foster a dependency upon them.

    Here at TFP, we are not out to sell you anything. All we want is for you to have a nice pool and without all the needless worries.
    TFP Moderator
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  13. #13
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    Re: No chlorine registering in my pool

    Shocking and "superchlorinating" mean the same thing. Shock is something you do to the pool, not something you buy. But poolstores won't tell you that. And they'll happily sell you "shock" even shock that is "chlorine-free".

    So I'm wondering too what kind of shock product you used.
    Also in the post above, you mentioned a new test kit - I was wondering what kind of kit?
    Helpful links: Pool School; The Pool Calculator; 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
    NO LONGER FRUSTRATED thanks to TFP.com
    http://www.PerfectlyClearPoolService.com

  14. #14
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    Re: No chlorine registering in my pool

    I have a 6 way test kit, ammonia test kit, nitrate, nitrite test kits. I use SKay products in my pool (used to be Sun). I used the pool calculator, it recommends 3 gallons of bleach, so we are going to try it. My pool store carries the liquid chlorine, but simply did not recommend it for my pool. And I have met my share of unethical pool people in the last 21 years. Thank you all so much for your time and effort in attempting to help me clear up this problem. We have spent about 350 dollars already this spring, attempting to get this right. Funny about the shock, as that is what it says on the label of the super chlorinator that I buy. Thanks everybody, you have been most helpful.. I will let you know when we get it right.
    ctlss: 45,000 gallons vinyl, I/G, 300 lbs sand filter, 2 HP Hayward Super Pump, Polaris 360 automatic pool sweep, 1/2 horse booster pump, 355,000 btu propane heater

  15. #15
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    Re: No chlorine registering in my pool

    Um, 3 gallons of bleach, which is around 4 -96 ounce jugs of Clorox, will only raise the FC in your pool to 4. You need to hit shock level.

    Your CYA level dictates your shock level - refer to the CYA/Chlorine chart - your shock level is 16-20. To reach 16, you will need 12 gallons of 6% or 16 small jugs, 8 large jugs (182 oz).

    If you can purchase the 10-12.5% pool store variety (assuming its fresh), it will mean less jugs to carry. If the pool store has been selling you liquid, if it was old stock, that might contribute to why you aren't getting a reading...
    Helpful links: Pool School; The Pool Calculator; 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
    NO LONGER FRUSTRATED thanks to TFP.com
    http://www.PerfectlyClearPoolService.com

  16. #16
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    Re: No chlorine registering in my pool

    Quote Originally Posted by ctlss
    and automatic chlorinator
    Can you please clarify if this means an inline chlorinator that uses Trichlor tabs/pucks or if this means a saltwater chlorine generator (SWG)?

    Also, did you notice the Cyanuric Acid (CYA) level dropping from when you closed the pool until when you opened it? With the chlorine level getting to zero and having algae growth, it's quite possible that bacteria converted some CYA into ammonia. That's why you've been asked to get an ammonia test kit from a pet/fish/aquarium store.

    If you want to see how much chlorine it will take in your pool before chlorine starts to hold, take a 2 gallon bucket of pool water and add 6% bleach to it where 1/4 teaspoon will be 10 ppm FC. Add the chlorine, mix, and test in an hour. If the chlorine has mostly been used up, then add some more, mix, retest in an hour. Repeat until the chlorine mostly holds. That will give you an idea of how much chlorine will be needed (scaled up for your pool, of course).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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  17. #17
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    Re: No chlorine registering in my pool

    Quote Originally Posted by ctlss
    I checked the ammonia and nitrates and they were zero. I have all the tests kits for my salt water and regular aquariums.
    Helpful links: Pool School; The Pool Calculator; 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
    NO LONGER FRUSTRATED thanks to TFP.com
    http://www.PerfectlyClearPoolService.com

  18. #18
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    Re: No chlorine registering in my pool

    Thanks. I missed that. The bucket test is still relevant to see how much chlorine it will take before it holds. Perhaps there are other chemicals to oxidize in the pool water other than ammonia. Could be some dead algae that isn't visible anymore or could be partially oxidized organic compounds that wouldn't show up in the tests.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  19. #19
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    Re: No chlorine registering in my pool

    Well I wonder if ammonia was present at some point but ctlss just isn't 'finished' with the process, KWIM?
    Helpful links: Pool School; The Pool Calculator; 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
    NO LONGER FRUSTRATED thanks to TFP.com
    http://www.PerfectlyClearPoolService.com

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