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Thread: still no chlorine reading !

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    still no chlorine reading !

    I just bought a house with a above ground pool. The pool measures 16 by 11 and it is 4 feet deep. The PH is 6.8 but no matter what I do I cannot get the chlorine up past a zero reading. The pool store says my CYA level is low, the pool is clear, I even used phosphate remover. I again shocked the pool last night, and again the chlorine reading is zero this morning. I really dont know what to do, after reading this site I dont trust the pool store. Should I put bleach into the pool? If so, how much???

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    Mod Squad JohnT's Avatar
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    Re: still no chlorine reading !

    Welcome to TFP!

    There are a couple of issues that can cause this. One is the use of test strips. They can bleach out at high chlorine levels making you think you have no chlorine. You can check for that by diluting a pool water sample 3 to 1 with tap water and testing the mixture.

    The more common cause is that something in the water is consuming your chlorine. It can be gone in just a few hours, so it's very common to put a bunch of chlorine into the pool at night and have nothing left by morning.

    Pool stores try to get by with "one size fits all" advice that is seldom appropriate for a particular situation. We emphasize understanding so you can do exactly what YOUR pool needs. Fortunately that understanding not only lets you do a better job maintaining your water, it is cheaper and easier.

    In order to really know what's going on, you need to do your own water testing, because the average pool store is not much better than rolling dice to get test results.

    You want to know your actual CYA level, then add enough chlorine to the pool to reach an appropriate shock level. You can determine that from the Chlorine CYA Chart Next comes the part that pool stores miss: Maintaining that shock level. We refer to the process for overcoming biological contamination of the pool as SLAM or Shock Level and Maintain to emphasize that ongoing nature of the process. You can read about it in the article SLAMing Your Pool

    Choosing your chlorine source depends on the rest of your water chemistry. All homeowner chlorine sources affect other areas of water chemistry. Powdered shock will either rapidly increase your CYA or your hardness. That's fine if you need to increase them, but not if they are already high. Bleach or liquid pool chlorine (the same thing in slightly different concentrations) add salt to the pool, but in most cases that is a desirable side-effect, so we tend to favor the liquid.

    To really have knowledge of your pool, you need your own test kit, and the cheap ones handicap you in ways you probably don't understand yet. We recommend either the Taylor K2006 (not the 2005) or the TF-100. You can buy either from TFTestkits.net. It will be the best investment you can make to make your pool care better and easier. It will pay for itself before this season is over.

    Skip the phosphate remover for now. 99.99% chance it was a complete waste of money. Pool stores like to sell magic elixirs to fix problems that don't exist.
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    Re: still no chlorine reading !

    Its not a huge pool, maybe about 5500 gallons. Someone told me the drain 1/2 & refill. Whould that help me to start over & get the chemicals in balance or am I wasting time & money?

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    Mod Squad JohnT's Avatar
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    Re: still no chlorine reading !

    Quote Originally Posted by joebas View Post
    Its not a huge pool, maybe about 5500 gallons. Someone told me the drain 1/2 & refill. Whould that help me to start over & get the chemicals in balance or am I wasting time & money?
    No way to know whether it needs draining without knowing the current water chemistry.
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    Re: still no chlorine reading !

    I received the testing kit today, here are my findings:

    CL <.5
    PH 7.2
    CYA 49
    FC 1.0
    CC 1.0
    TC 2.0
    TA 130

    I have shocked the pool a couple of times at night only to have almost zero chlorine in the morning

    I also added two gallons of clorox bleach the other day only to have just about a 0.5 CL reading 5 hours later...

    Also used (and wasted the $$$) on phosphate remover last week.

    I don't know why the pool in not holding unto the chlorine....

    HELP!!!

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    Re: still no chlorine reading !

    With a cc of 1, you have something (algae, more than likely, just not visible yet), trying to take hold. You need to read up on how to slam your pool in Pool School. This will require testing and adding chlorine (Bleach) every hour or as often as you can, to bring it back to shock level until the chlorine holds overnight and you pass the OCLT. If your cya is about 50, then your shock level is 20. A couple jugs of chlorox a night is not enough to kill whatever is trying to grow. You need to bring your shock level to 20 and keep it there, testing and adding chlorine every hour or so to MAINTAIN the level of 20 until you pass the overnight test and have less than .5 cc's.
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    Re: still no chlorine reading !

    Use the handy dandy Pool Math to figure out how many gallons your pool holds. Plug in your numbers and what your goal number is. For example, if your chlorine reading is 1, put that in the fist box, then put 20 in the 2nd box. Then put what strength bleach you are using and hit calculate. Presto, it will tell you exactly the amount you need to reach your target of 20. Then you must continue to do this every hour or so until you pass the OCLT.
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    Re: still no chlorine reading !

    Hi joebas and welcome to TFP

    How did you get CYA of 49? Can you confirm this test result?

    There is a link to TFP Test kit youtube videos to help guide you through the tests.

    No doubt you need to SLAM the pool, but we need to verify the CYA first.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    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.

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    Re: still no chlorine reading !

    I will retest the CYA & post the results.

    Does SLAMing cause the DE filter to get clogged? Will I need to go through multiple backwashings?

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    Re: still no chlorine reading !

    Quote Originally Posted by joebas View Post
    I will retest the CYA & post the results.

    Does SLAMing cause the DE filter to get clogged? Will I need to go through multiple backwashings?
    Not as a result of the chlorine addition; instead, it's a result of removing the dead biomass, or anything in the water that might precipitate out, that the chlorine has reacted with.

    I have very high iron levels in my fill water; thus, I precipitate out the iron and then kill the algae unless I take a very careful approach to treating the fill water - so the iron plugs my sand filter and then the dead biomass etc...

    Once you get your water chemistry balanced, things will go very smoothly so stick in there and follow the advise of the Moderators/Experts.
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    Re: still no chlorine reading !

    I tested the CYA again this morning while the pool filter was off since last night. Today's CYA level was 55

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    Re: still no chlorine reading !

    Soooo I started SLAMing yesterday & probably added to much bleach since my FC was over 27 last night. This morning at 6:30 it was 23, at 10:00 it was 23 & at 1:00 (pool is in the blazing sun all day) it is 20. I guess I'm headed in the right direction. Keep adding bleach today until I pass the overnight test?

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    Re: still no chlorine reading !

    Yep. For a CYA of 50, add as much bleach as required to keep your FC at 20 (or slightly above), until all three tests are passed.
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    Re: still no chlorine reading !

    I finished the SLAMing last week & everything seems to be under control now. If I did it right (using the pool match calculator) I figured my pool has 4500 gallons (16x11x4ft) & a little less than one cup of Clorox should increase my FC by 1ppm. I have heard people say that using bleach will fade the liner. Am I in danger of bleaching the liner if I'm trying to keep my FC at around 6/7 ? Depending on my CYA level (which is currently 50) should I switch between the triclor tabs & Clorox?

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    Re: still no chlorine reading !

    Quote Originally Posted by joebas View Post
    I finished the SLAMing last week & everything seems to be under control now. If I did it right (using the pool match calculator) I figured my pool has 4500 gallons (16x11x4ft) & a little less than one cup of Clorox should increase my FC by 1ppm. I have heard people say that using bleach will fade the liner. Am I in danger of bleaching the liner if I'm trying to keep my FC at around 6/7 ? Depending on my CYA level (which is currently 50) should I switch between the triclor tabs & Clorox?
    No danger at all if your pour the bleach into the return stream so it mixes and disperses. If you just pour a bunch in in one spot, it can settle on the bottom and bleach, but if you mix it as it goes in, no trouble at all.

    Trichlor pucks will raise the CYA level with each puck you add, which means you'll need to maintain higher FC, which means you'll need more pucks, which raises CYA, which means you'll need to maintain higher FC, which means you'll need more pucks, which raises CYA, which means.... you're caught in a vicious spiral that ends with a green pool that resists clearing and leaves you with a recommendation to drain and refill.

    Trichlor is also acidic. So you'll end up needing to raise pH and probably add a bunch of baking soda to keep TA up.

    Pucks will keep for years if the bucket is kept closed. Save them for vacation, or to raise CYA to replace losses due to backwashing and splashout or for startup next season.
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    Re: still no chlorine reading !

    Great Thanks!! I just bought a house that has a pool & this is my first pool season. After a couple of trips to the 'pool store' I luckily came across this site (which I have already told friends about)....THANK YOU, THANK YOU for the excellent information available on here!!!

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    Re: still no chlorine reading !

    You're welcome. Folks on TFP love to help
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    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.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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