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Thread: Some questions about my TF-100 test results

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    Some questions about my TF-100 test results

    Hi - I recently started one other post under "getting started", where I asked for advice regarding our high CYA and Calcium levels. I ordered the TF-100 test kit, and have been enjoying it, though I still have some questions about it as I try to test the water accurately. Our numbers seems so off that I'm wondering if it's user error for some of them.

    One reason I feel skeptical is that our long-time pool maintenance professional thinks I'm crazy when I mention that we need between 11 and 18 ppm of chlorine if the CYA is at 140. He says that would be like chlorinating 3 pools. It's hard to know who to trust! He has always kept the pool looking great, and does advise draining it soon, but then has me questioning the chlorine to CYA ration.

    I did the CYA test again just now, and what happens is that I can no longer see the black dot well before I even reach the first line on the cylinder - at 100 - so I just add (approximately) the difference between where I stop seeing the black dot to 100 to get 140. Does that sound correct? (Another professional who I just spoke to on the phone mentioned that CYA tests stop at 100 anyway - IF I'm remember correctly the conversation I had with him some time ago), but that is also making me wonder if I'm doing something wrong.

    In addition, I have a question about the Chlorine Drop test. The instructions that came with the kit say that you add R-0871 a drop at a time until the solution turns "completely clear" again. I realized today that my solution never turns completely clear again, it just turns colorless, but it's cloudy looking. No pink at all, but cloudy. Is that what I'm going for? To check, I kept adding drop after drop to see if it would turn "clear" again, but it never did, so I'm wondering if I need to stop at the cloudy colorless that I'm currently getting, or at clear, which I don't seem to get at all.

    Thank you!
    Shannon
    In-ground, plaster, approx. 16k, cartridge filter system (Sta-Rite System 3 Modular Media Filter)

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    Re: Some questions about my TF-100 test results

    Colorless is the goal on the chlorine drop test. Don't keep adding drops.

    The CYA test does stop at 100, but there is a way to do a diluted test to get a more accurate number. I'm sure someone will post those directions soon as I've never done that.

    It isn't unusual for someone in the pool industry to question TFP practices because it isn't possible for someone servicing pools to be totally TFP and service a pool once a week.

    TFP works. Just read, learn, and ask questions. We are here to help.


    Lisa P.
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    [It is better to know how to learn, than to know. - Dr. Seuss[/I]

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    Re: Some questions about my TF-100 test results

    Howdy neighbor! I'm in San Marcos.

    I've got the K2006 kit, but I think they're pretty similar. On the chlorine test, just get to colorless, not clear.

    I'm having an issue with CYA myself - not sure what the reading actually is, it's so high. I'm going to try an alternate method to see if I get better results. Maybe our water is already chock full of CYA?
    16 x 32 IG plaster pool, 23k gallons, built 1992, DE filter, Pentair VS pump, IoThyngs controller, Taylor 2006 test kit, SoCal water restrictions
    Newbies with green pools, see SLAM and Recommended Test Kits. My company: IoThyngs

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    Re: Some questions about my TF-100 test results

    You are doing much better than you think. You Pool guy does not understand fully the FC/CYA relationship as many in his industry do not either.

    Basically, what you have is an unmanageable pool (even though it may look good right now, controlling it economically is almost impossible).

    1. Diluted CYA test - blend a mix of pool water and tap water half and half. You now have a 50% diluted pool sample.
    Next, take that pool sample and put it in the CYA mixing bottler to the bottom of the label.....fill the rest of the mixing bottle with R-0013 CYA reagent.

    Now, simply perform the test as per instructions but you will multiply your results by 2 to get your CYA. Easy Peasy.

    2. Another way to explain the chlorine drop test is...."Add drops until you see NO further color change. Then subtract that last drop which made no color change from the other drops and that is your final result. For example, you add drops to a count of 22 and it looks like all the pink is gone. Use one more drop to confirm there is no additional color change and, if so, don't count that drop so your FC is 11 ppm.

    3. I assume you are manually chlorinating the pool. If so, I suggest you make plans to drain enough of your pool to get to 50 ppm CYA. The results of the diluted CYA test should tell you how much you need to drain.

    You'll have to make the call as to who you believe. Read the thousands of posts here from folks who follow what we teach and make your decision.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Some questions about my TF-100 test results

    You can dilute the pool water sample by mixing a cup of pool water with a cup of tap water and using that to mix with the CYA test reagent. Perform the test as directed and when you read the result double it to get the approximate CYA reading. A diluted sample will not be as accurate as an undiluted one, but it will give you a good idea how high the CYA is.

    Our advice on pool care is backed by science, and the real life experience of thousands of members. Our methods work. You need to decide if you are going to follow TFP guidelines or your pool guy's guidelines. You can't mix and match between the two and be successful.

    I understand it can be a difficult decision to make, but you have to pick one or the other. I encourage you to pick TFP. It is very empowering to know what your pool needs and how to take care of minor problems that pop up. You've already taken the first step by purchasing an awesome test kit!
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    Re: Some questions about my TF-100 test results

    Amail, There is no CYA in your tap water. It only gets in your pool if you or a previous owner puts it there. I don't want to hijack OP's thread so start a new thread or go to your old one and add on your questions.....you'll get lots of help, we promise
    Dave S.
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    Re: Some questions about my TF-100 test results

    If the dot is disappearing before reaching 100, then it is over 100, but we don't know how far. To test it diluted, use half pool water and half tap water. pour that mixture to the mark for pool water, then add reagent, shake and test. Multiply that number by two. It won't be as accurate, but will give you an idea where your CYA is at.

    I understand PM guy being skeptical, But chem geek has explained the correlation between CYA and chlorine. That is why they stress CYA levels here. Pool stores and probably your PM guy would have you chlorinate with tabs which contain CYA and eventually your CYA is so high your "normal" chlorine level is no longer controlling algae and they start selling you all kinds of magic formulas to "correct" it. Eventually you have to do water replacement (which was their fault to start with)

    From your other thread, did you mention what you were chlorinating with. Bleach or liquid chlorine is what we recommend here.

    He apparently understands too much CYA is bad (I assume that's why he recommends draining, maybe it's for another reason ?)

    Bottom line, if your CYA is that high it needs to come down, which involves replacing water.

    Also as Pogueld mentioned, your looking for colorless, the water may look cloudy from the powder, as long as the pink is gone. Also I might add, that if you let the sample sit for a few minutes it will start to turn light pink again, that's normal. That's why I suggest not to wait long between testing FC and CC.
    Si -central Mo. 32' x 16' -- 3'4" to 6' deep Vinyl liner - 16,500 Gals : Triton II filter -Duraglass 2 hp pump - 1 speed : SI-30 salt generator
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    Re: Some questions about my TF-100 test results

    Quote Originally Posted by duraleigh View Post
    You are doing much better than you think. You Pool guy does not understand fully the FC/CYA relationship as many in his industry do not either.

    Basically, what you have is an unmanageable pool (even though it may look good right now, controlling it economically is almost impossible).

    1. Diluted CYA test - blend a mix of pool water and tap water half and half. You now have a 50% diluted pool sample.
    Next, take that pool sample and put it in the CYA mixing bottler to the bottom of the label.....fill the rest of the mixing bottle with R-0013 CYA reagent.

    Now, simply perform the test as per instructions but you will multiply your results by 2 to get your CYA. Easy Peasy.

    2. Another way to explain the chlorine drop test is...."Add drops until you see NO further color change. Then subtract that last drop which made no color change from the other drops and that is your final result. For example, you add drops to a count of 22 and it looks like all the pink is gone. Use one more drop to confirm there is no additional color change and, if so, don't count that drop so your FC is 11 ppm.

    3. I assume you are manually chlorinating the pool. If so, I suggest you make plans to drain enough of your pool to get to 50 ppm CYA. The results of the diluted CYA test should tell you how much you need to drain.

    You'll have to make the call as to who you believe. Read the thousands of posts here from folks who follow what we teach and make your decision.
    I always love your explanations.


    Lisa P.
    26,000 IG, pebble tec, flagstone, pentair Triton II TR100 sand filter & VS+SVRS 3hp multi-speed pump, Intellichlor IC-40 SWG, Pentair Booster Cleaner, spillover spa, waterfall, Taylor K-2006 testkit
    [It is better to know how to learn, than to know. - Dr. Seuss[/I]

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    Re: Some questions about my TF-100 test results

    Thank you! This is all very helpful. We have stopped using tabs altogether (to avoid adding even more CYA) and are just using liquid chlorine, but from reading other posts it sounds like CYA doesn't just "go away" quickly, so we do plan to drain. BUT... We've also read that it isn't a good idea to drain a plaster pool during hot weather, so we're hoping to wait until the fall. Is that accurate, to wait for cooler weather?
    In-ground, plaster, approx. 16k, cartridge filter system (Sta-Rite System 3 Modular Media Filter)

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    Re: Some questions about my TF-100 test results

    Quote Originally Posted by Shannonlf2000 View Post
    Thank you! This is all very helpful. We have stopped using tabs altogether (to avoid adding even more CYA) and are just using liquid chlorine, but from reading other posts it sounds like CYA doesn't just "go away" quickly, so we do plan to drain. BUT... We've also read that it isn't a good idea to drain a plaster pool during hot weather, so we're hoping to wait until the fall. Is that accurate, to wait for cooler weather?
    I can't speak to the safety of draining, but if you do not have algae or combined chloramines (more than 0.5ppm), I think it would be manageable to maintain 11+ ppm FC for a few months. Yes, it will take more chlorine to get above that initially, but with CYA that high you won't lose as much per day so less to maintain it. The problem comes if you need to SLAM -- you'd have to get to 55ppm FC, which would take a lot of chlorine. At that point draining before you SLAM is recommended, but if you can hold off until the winter rains start (hopefully!!!) that may be a prudent choice.

    I went from CYA 80 last year to CYA 40, and while it requires lower FC levels, the daily FC drop is definitely causing me to use more chlorine than last year, so I'm bumping CYA up to 50-60 to get a balance. I think California with our full sun all day all summer calls for going to the higher end of the recommended range.
    21000gal IG plaster, Sacramento CA area (late 1950s/early 60s)
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    Re: Some questions about my TF-100 test results

    I started with 220-240 CYA. Hard to be more precise that than when you dilute 3 and 4 times. We also had water restrictions that year, with penalties and the threat of having a flow restrictor put on my meter at my expense. So... I had to maintain the FC up around 20. It wasn't easy and I don't recommend it but it can be done. The pH test is always questionable with FC that high, but we swam in it with no ill effects.

    Replacing water would be the ideal solution, but we both know that will just draw the wrath of the water company and your neighbors. I slowly lowered the CYA (and CH) by using pool water on the lawn and using what would have gone to irrigation to refill the pool. Basically, I ran the irrigation water through the pool first. Yes it was a PITA. It was a great day when we finally had a big rain storm and I was able to divert a raingutter downspout to the pool and replace 10% or more with CYA-free and CH-free water... for free!

    Why do you still have a "pool professional"? You have a test kit and brushing and vacuuming don't require a whole lot of specialized skill. I had to go buy a brush head and a vacuum and a hose and was repaid after one month of not paying the pool service.
    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: Some questions about my TF-100 test results

    Quote Originally Posted by Richard320 View Post
    I started with 220-240 CYA. Hard to be more precise that than when you dilute 3 and 4 times. We also had water restrictions that year, with penalties and the threat of having a flow restrictor put on my meter at my expense. So... I had to maintain the FC up around 20. It wasn't easy and I don't recommend it but it can be done. The pH test is always questionable with FC that high, but we swam in it with no ill effects.

    Replacing water would be the ideal solution, but we both know that will just draw the wrath of the water company and your neighbors. I slowly lowered the CYA (and CH) by using pool water on the lawn and using what would have gone to irrigation to refill the pool. Basically, I ran the irrigation water through the pool first. Yes it was a PITA. It was a great day when we finally had a big rain storm and I was able to divert a raingutter downspout to the pool and replace 10% or more with CYA-free and CH-free water... for free!

    Why do you still have a "pool professional"? You have a test kit and brushing and vacuuming don't require a whole lot of specialized skill. I had to go buy a brush head and a vacuum and a hose and was repaid after one month of not paying the pool service.
    Oh Richard, what a creative solution for your water woes! and ditto to no need for a Pool professional. BE your OWN pool professional.


    Lisa P.
    26,000 IG, pebble tec, flagstone, pentair Triton II TR100 sand filter & VS+SVRS 3hp multi-speed pump, Intellichlor IC-40 SWG, Pentair Booster Cleaner, spillover spa, waterfall, Taylor K-2006 testkit
    [It is better to know how to learn, than to know. - Dr. Seuss[/I]

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    Re: Some questions about my TF-100 test results

    Quote Originally Posted by Shannonlf2000 View Post
    One reason I feel skeptical is that our long-time pool maintenance professional thinks I'm crazy when I mention that we need between 11 and 18 ppm of chlorine if the CYA is at 140. He says that would be like chlorinating 3 pools. It's hard to know who to trust! He has always kept the pool looking great, and does advise draining it soon, but then has me questioning the chlorine to CYA ration.
    Your "pool maintenance professional" does not understand the chemistry behind the chlorine/CYA relationship. He apparently does not understand that with 11 ppm FC and 140 ppm CYA that 99.4% of the FC is chlorine bound to Cyanuric Acid in chemicals called chlorinated isocyanurates and that these have virtually no disinfection capability and less than 1/150th the oxidizing capability of hypochlorous acid. They are for practical purposes inert, but they do provide a reservoir or reserve of chlorine that is released as hypochlorous acid gets used up. So the active chlorine (hypochlorous acid) level in the pool is proportional to the FC/CYA ratio (technical derivation of this is in this post).

    It is the active chlorine (hypochlorous acid) that kills pathogens and prevents algae growth so the FC number by itself is completely useless to look at. One must look at the FC/CYA ratio to understand whether one has enough active chlorine in the pool to kill algae and provide effective disinfection and oxidation of bather waste.

    Because of the chemical equilibrium between unbound active chlorine and chlorine bound to CYA, 11 ppm FC with 140 ppm CYA has the same active chlorine (hypochlorous acid) as 2.4 ppm FC with 30 ppm CYA. This is what your "pool maintenance professional" does not understand. He thinks that only FC matters and that is absolutely, positively not true. If he has taken a CPO course, then he should read the first post in the thread Certified Pool Operator (CPO) training -- What is not taught.

    You can test higher CYA levels by diluting the pool water sample with tap water (since it has no CYA in it) and then multiplying the result from the test by the dilution amount so a 1:1 dilution of half pool water sample with half tap water would get its CYA measured result multiplied by 2.
    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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    Re: Some questions about my TF-100 test results

    When I dilute the pool water with tap water and multiply the results by 2, I get about 280 CYA!!!!
    In-ground, plaster, approx. 16k, cartridge filter system (Sta-Rite System 3 Modular Media Filter)

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    Re: Some questions about my TF-100 test results

    Uh-oh. You have a few choices. Maintain your chlorine at about 35 ppm at all times, perform partial drains and refills until your CYA is reduced to around 50 ppm or have a company perform reverse osmosis filtration to remove the CYA. And hope you never have to SLAM, the shock level for FC will be about 110 ppm. Chlorine CYA Chart

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    Re: Some questions about my TF-100 test results

    Shannon,

    There is something amiss in your 280 calculation. The test only can measure up to 100 and for you to get a 280 reading meant that you measured at 140; how did you come up with that number?
    5900 G Fiberglass IG pool (circa 1990), SWG Hayward Aqua Rite GoldLine (2013), IntelliFlo Variable Speed Pump (2013), Hayward Pro Sand Filter (circa 1990), Well water (no iron or other metals fortunately), test with Taylor K2006C, Charleston, SC

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    Re: Some questions about my TF-100 test results

    Quote Originally Posted by Shannonlf2000 View Post
    When I dilute the pool water with tap water and multiply the results by 2, I get about 280 CYA!!!!
    Shannon,

    Just wondering how you got 280 CYA.. CYA only goes to 100 and that times 2 would only be 200.. Did you dilute it 25% 1/4th pool water and 3/4 tap? it would be x4
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    Re: Some questions about my TF-100 test results

    I diluted it 50% pool water and 50% tap, the reading came out almost exactly the same as when undiluted - about 140 (it doesn't even reach 100 on the black dot reading tube - it's about 40 below 100, hence 140) - then I multiplied by 2. What did I do wrong?
    In-ground, plaster, approx. 16k, cartridge filter system (Sta-Rite System 3 Modular Media Filter)

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    Re: Some questions about my TF-100 test results

    I don't know if I've told chem geek how much I love him, but if you take his advice you won't go wrong.
    Cornelius Monterey Steel/Resin AG 18' round (approx. 7600+gallons) Hayward veri-flo SWG w/sand filter.Testing w/ TK2006 using Speed stir.

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    Re: Some questions about my TF-100 test results

    Quote Originally Posted by Shannonlf2000 View Post
    I diluted it 50% pool water and 50% tap, the reading came out almost exactly the same as when undiluted - about 140 (it doesn't even reach 100 on the black dot reading tube - it's about 40 below 100, hence 140) - then I multiplied by 2. What did I do wrong?
    I'm not sure what you mean by, "It's about 40 below 100"...can you clarify this any?
    5900 G Fiberglass IG pool (circa 1990), SWG Hayward Aqua Rite GoldLine (2013), IntelliFlo Variable Speed Pump (2013), Hayward Pro Sand Filter (circa 1990), Well water (no iron or other metals fortunately), test with Taylor K2006C, Charleston, SC

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