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Thread: Pool not retaining chlorine

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    Pool not retaining chlorine

    Hello everyone –

    We are having a continuing issue with our pool. I’m providing background for those who want to know if we have tried various options and in the last paragraphs will pick up from yesterday. We are in a rental house and utilized the pool here last year. We had multiple recurrences of metal issues, but for the most part we limped through the year and ran the water to get tested every few days and addressed what needed to be addressed. I have no idea how old the pool is.

    We are located in Central New Jersey and needless to say the weather here the last month has been atrocious. It is either cold and raining, with thunderstorms or hazy hot and humid. When we first opened the pool the water was clear but there was a lot of debris in the pool (we were hard hit in our area by Sandy and multiple other windy storms). The company I hired the pool to open the pool did not clean it – lesson learned. We vacuumed normally not realizing at the time that there was a vacuum to waste option and within a day the filter was not doing it’s job and the water was getting cloudier by the day.

    After giving it a few days (and not pushing it because of the horrid weather) we finally called a local pool service. He came and we started using things like stabilizer, shocking the pool and all in all attempting to get a handle on the levels. He came one day and shocked and within a day the pool was brown. We knew from our experience last year that was metal so we treated for that.

    Still the pool would not get clear. Finally the pool service figured we needed to replace the sand and oh boy were they right (what came out of that filter was disgusting to say the least). Within a day the water was not crystal clear, but was much better than it had been.

    Our lingering issue since then is that the pool will just not get clear. It seems like we are dumping a huge amount of chemicals into it. As of yesterday, the pool was cloudy with a nice shade of green. At no point through this whole process has the pool ever registered any chlorine on the test strips (AquaCheck) that we are using.

    Yesterday morning, we dumped 5 lbs of Durachlor shock into the pool first thing in the morning. We also used 16oz of Ultra Brite clarifier. By late afternoon the pool looked no different. (Temps were in the 90s with blazing sun if that helps.)

    Late in the afternoon I took the water to get tested by the pool service we are using. Here are the numbers that were provided to me:

    Free Chlorine - .43ppm
    Total Chlorine – 1.28 ppm
    Combine Chlorine - .85ppm
    pH – 6.5
    Hardness - 39ppm
    Alkalinity – 14ppm
    Cyanuric Acid – 128ppm
    Copper – 0ppm
    Iron – 0ppm

    If there are other test results that you’re looking for, I’ve included anything they provided to me on the printout that I’m looking at ?

    They ‘prescribed’ the following – 12 pounds of alkalinity and 4 pounds of Durachlor shock. By this morning, the green tinge was mostly gone, but the cloudiness remained. I stopped at the store and had the water retested, and the pH and alkalinity looked good according to the woman there (I have no updated results, just from what she saw). She agreed that I could add more shock to the pool. She told me to go with 3 pounds (so I pushed my luck and did 4).

    I also added earlier today about 12 ounces of clarifier. By this evening, there was maybe a slight improvement in the shallow end of the pool (3 feet deep on that side) but still obvious cloudiness in the bottom of the deep end and minimal improvement. Tonight, since we are looking at high temps all day today and tomorrow (90+ and blazing sun again), we added 5 more pounds of Durachlor shock. (A quick google tells me that Dichlor is the term on this site that is probably closest to what I’m using.)

    Throughout much of this process, the filter was on a timer set to turn on at 6am and off at 6pm. Over the last few days, since we’ve taken a more hands on approach (and stopped waiting for the pool guy), I’ve had it running 24 hours a day for the last two days.

    Outside of this, normal chlorination is taking place with tablets in a floater (we are keeping it as stocked as possible), and as of two days we started applying tablets directly into the skimmer to give it a boost. For the first time all season, I can actually get a whiff of chlorine when I walk out to the pool. Not that I want it over chlorinated by any means, but at least I know I’m not losing my mind and it’s actually going into the pool.

    I know for a fact that I need to order a better test kit then these test strips, and plan to do that next. (It looks like there are varying test kits on the site in everyones signature here - any recommendations for my situation are appreciated.) I've seen one or two other posts similar to this and am hoping that someone can help me out or at the least get me in the right direction.

    Many thanks for your help,
    Lorraine
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

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    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    Welcome to TFP!

    You definitely will save yourself a lot of confusion and money by staying out of the pool store.

    Your CYA is likely much too high and all the Dichlor and trichlor tablets are making the problem worse.

    There are only two test kits we recommend. The TF100 costs a bit more, but you get more of what you actually need ... so that is the better deal.

    Order the test kit.
    Read Pool School.
    Plan or start to replace water to lower the CYA.
    Jason, TFP Moderator
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    Re: Pool not retaining chlorine

    In addition to what jblizzle already mentioned, your PH is way too low. You never want to allow the PH to get below 7.0, or preferably 7.2. PH below 7.0 can damage the pool if it stays low for too long.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Pool not retaining chlorine

    Thanks everyone. I'm ordering the test kits now! How can I address the low pH? Also is there anyway to treat the high CYA without draining/refilling a decent amount of water?
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

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    Re: Pool not retaining chlorine

    use borax to raise the Ph, as for reducing the CYA the only way is to drain/refill
    13500 gallon AG, build late 90's, Hayward S220T sand filter,1Hp aqua coastal
    Gasser BBQ broilmate 155154 LP, Smoker CGK (akorn)

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    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    Read the recommended pool chemicals article in Pool School.

    Drain and refill is usually the only way to reduce the CYA. In very limited areas, you can get a reverse osmosis treatment done for $300+
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Pool not retaining chlorine

    Quick update with some additional questions...

    As of this morning the pool looks 'slightly' more clear on the deep end, so at least my late night 5lbs of powdered chlorine didn't make anything worse - yet.

    As for the pH, I'm off to buy Borax this morning. Per the pool calculator, the pool I have is about 38800 gallons. It's 18x36x8 feet deep (shallow side is only 3ft). Other pool places have typically estimated it at 28000 or 30000. If my current test is showing 6.5, and this is prior to having added an additional 10 lbs of shock, I'm considering that 6.5 test result to be a little on the high side for today. So I'm thinking of taking the recommended Borax dosage from The Pool Calculator for the larger volume - which is 823 oz. Does that sound like the right approach? Is it okay to say add half, retest in the morning and then add the other half? I've educated myself with the BBB page for Beginners so I know exactly where to put the Borax (sometimes I swear that is half the battle), so I will administer that today

    Next question is as I'm reading through this thread and the forum as a whole, it seems like liquid bleach is really the key to helping manage the chlorine levels without effecting the other levels. The pool service guy I was using recommended using liquid shock when we first started having issues and administering it directly into the skimmer since I have a liner pool. Do I need to have any concerns about administering liquid bleach into a liner pool? And on edit, I just answered that myself by digging up an old thread that mentions to add it in front of a return jet while it's running.

    Case closed on that one and a brief follow up - do I need to wait any period of time prior to switching to the liquid bleach since we've used so much of the powdered stuff over the last few days?

    I can't stress enough the level of knowledge that I have today compared to yesterday when I first signed up, logged in and gave you my diatribe. This forum is fantastic!!!

    Lorraine
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

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    Re: Pool not retaining chlorine

    Is it okay to say add half, retest in the morning and then add the other half?
    Absolutely the correct thing to do. Because of some variables, poolcalc cannot give you a dead on pH adjustment dosage every time so it is STRONGLY suggested you make large changes in 50% increments or so. Better to sneak up on your goal than overshoot with a big dose.

    Thank you for the nice words about this group of folks on here......they know their stuff, don't they?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    You only need to wait 30-60 minutes or so between various chemical additions. Likely even less would be fine. Once the chemical is dispersed in the water, it is fine to add the next.
    Jason, TFP Moderator
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    Re: Pool not retaining chlorine

    Quote Originally Posted by Metsy10
    Per the pool calculator, the pool I have is about 38800 gallons. It's 18x36x8 feet deep (shallow side is only 3ft). Other pool places have typically estimated it at 28000 or 30000.
    You forgot to use an average depth. You need to put in 5.5 ft for depth into the pool calculator. Using 5.5 ft, it calculates 26,700 gallons.
    From The Pool Calculator
    If the depth varies, use the average depth of the pool. A good approximation is the shallow end depth plus the deep end depth divided by two. Irregularly shaped pools can be approximated by estimating the average length and width and using rectangular.
    30,000 gal, 20 x 40 ft vinyl, IG, installed 2006
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    Re: Pool not retaining chlorine

    Thanks laprjns! I've reset it so it retains those values.

    Just wanted to post a quick update so I can let everyone know what I’ve done so far. This way I won’t forget it either.

    Last night, I added 5 boxes of Borax (total of 380 oz). I’ve got an order of 12 boxes coming from Amazon, should be here Wednesday (bought out the grocery store). As of this morning, the pH reading on these horrible test strips is showing better results, but not quite there yet. However, given the reading that the only true test result I have is from Friday, and it’s from the pool store that I no longer trust, I’m concerned about over doing it. My test kit (the TF-100) shipped today and should be here by Wednesday as well. Gives new meaning to “Christmas in July”! So I will run the gamut of tests on Wednesday unless you all recommend that I bump it up more until then, since it’s my understanding low pH can cause much damage. If I am color coding the strip accurately, it's showing between 6.2 and 6.8. Can I wait until Wednesday to add more Borax, or do I need to do it more urgently than that? (I'll hit another grocery store if I do.)

    As of about an hour ago, I also added two containers (total of 242 oz) of Clorox bleach (my pool has shown 0 chlorine on test strips all season). The Pool Calculator is recommending between 4 and 5 gallons so my two is following the 50% rule.

    I do have a question though, as it seems this is a new ‘calculation’ on their bottles and I did not pay nearly enough of attention in chemistry in high school for this. The Active ingredient is Sodium Hypochlorite – at 8.25%. The note at the bottom of the ingredients mentions that it yields 7.85% in available chlorine. When utilizing the Pool Calculator, which number should I be entering as the percent of chlorine?

    Is it Wednesday yet?

    Thanks again!
    Lorraine
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

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    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    Use 8.25%.

    Also, generally you want to add the full recommended amount of bleach (not sneak up on it like the other chemicals). It is critical to maintain adequate FC, and even if you overshoot a little, the sun will lower it within a couple days and no harm done.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Pool not retaining chlorine

    Thanks so much Jason. I used the chart here - pool-school/chlorine_cya_chart_shock and determined my FS should be about 12 (based on practically no FC and a high level of CYA). To get it there from the original .43 test result I had from Friday evening, I added 491 ounces - 242 at about 1pm this afternoon, another 121 when I saw your response later this afternoon and another 128 now. (Figured the extra 20 ozs would not be enough to be harmful, and that made the math easier on my brain since that was just the whole bottle).

    When would be a good time to test the FC again? I'm still using the strips but figured may as well use them up anyway since my new test kit gets here in just a few days.
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

  14. Back To Top    #14
    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    If you are only using strips, then it does not really matter when you test because the result is not believable anyway
    Being exact with the bleach really is not that critical especially with the larger pools. Likely going to the nearest half bottle is good enough.

    If you had a good kit, you would want to retest about an hour after you added the bleach (or any chemical really) to verify that you hit your target.

    Being
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: Pool not retaining chlorine

    I wanted to point out something, because how I read one of your posts above there may have been some confusion, all depending how I read it.

    Liquid chlorine and liquid bleach are the same thing. The only difference is Bleach is generally 6% or 8.25% where liquid chlorine is generally 10% or 12.5% You just need to find what type and who/where offers the better value.

    With a pool your size, how many jugs you need to buy/carry/keep on hand can play a role in deciding what strength you use. Sometimes its even called liquid shock, just check the bottle and anything Sodium Hypochlorite is what your after.

    Heres a calculator (created by a member) to compare the costs per oz across the various strengths.
    http://poncatechsquad.com/dan/calc/chlorine/
    12500 gallons, 24 foot round above ground
    Hayward Sand filter, Pentair OptiFlo 1HP 2-Speed pump

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    Re: Pool not retaining chlorine

    Hi everyone!

    My test kit came yesterday - so excited! I did the following tests so far:

    Alkalinity - 100
    pH - 6.8
    Free Chlorine - 0 (<---- not a typo, an actual test result)
    CYA - 100

    So based on this, and by plugging values into the pool calculator, I am adding 304 oz of Borax to raise the pH. From what I am seeing on this chart (pool-school/chlorine_cya_chart_shock), I need to up my FC to 12 to compensate for the high CYA. My question is am I interpreting that correctly?

    The pool calculator is calling for 483 oz of 8.25% bleach to go from a 0 to a 12. Given that the CYA is a little high still (but not the 128 my pool company tested it as ( ) ), we are continuing to vacuum to waste and to run the hose to replace the water as best as we can.

    Thanks again everyone!
    Lorraine
    New Jersey based 18'36' IG Liner Pool
    Emerson 1081 Pump 1.0 HP, Hayward DE 4800 Filter
    Approx. Gallons - 27500. There is no spa, no salt, no heater.
    Results produced by TF-100 Test Kit, also have an iron kit

  17. Back To Top    #17
    Mod Squad jblizzle's Avatar
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    Re: Pool not retaining chlorine

    Well, the problem is your CYA may be WAY over 100ppm. Try that test again starting with a 50/50 mix of pool and tap water, then the reagent, and double the result.

    What does the water look like?
    Likely you should replace a bunch of water to lower the CYA before you bother to start adding chlorine (you are reading the chart correctly).
    You probably should get the pH up some first though.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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