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Thread: Incorrect CH results

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    Incorrect CH results

    Did my weekly tests this morning and came to the realization that I've been testing CH incorrectly. I've got a Taylor DPD test kit and have been stopping at purple instead of blue for the CH test.

    I took a water sample to Leslie's this morning with my test results and all results match except for CH which they tested at 680ppm!

    Rest of test results:

    Ph: 7.6
    FC: 5.0
    CC: 0
    TA: 60
    CYA: 50

    I tested my fill water once I got home and realized that it too is very high (>400)

    Since drain and refill does not seem to be an option what's everyone's take on sequestrants in the short term, and using a conditioning service to get it down longer term. Another option that I thought of is to use a water softener, but I'm not sure that this would be a good thing.

    Any suggestions would be appreciated.

    Jim
    18 x 28 with 8x8 Spa with Vanishing Edge Dam wall, Pentair 4 x 160 & 2 Whisperflo, Badu Swimjet SuperSport, Pentair 400Kbtu Minimax, 80sqft DE CAT 1000 PH Controller with Stenner Pump/Tank combo

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    JasonLion's Avatar
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    Re: Incorrect CH results

    You can compensate for high CH levels by lowering your PH and keeping TA down around where you have it now. Water temperature also plays a role. For example, in mid-summer with the water around 90 and your current numbers you only need to keep the PH between 7.0 and 7.7 to be alright. When the water is colder the PH can go higher, for example with the water at 60 you can keep the PH between 7.2 and 8.0 without any real problems. All of these numbers assume you are not using borates and don't have a SWG. Similar things work in those cases, but the numbers would be slightly different.

    Then, over the long term, you can work on lowering the CH level as convenient.

    When the test sample turns purple it is called a floating end point. You may want to consider getting a magnetic stirrer. They help avoid floating end points and greatly speed up the process of testing high CH levels.
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    Richard320's Avatar
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    Re: Incorrect CH results

    Where's Simicrintz..... He's running late

    680 is no problem - I've been fighting high CH for a year and am down in that neighborhood now and very excited about it. Rainwater has no Calcium. Aim your downspouts into the pool. It works even better if you can pump some water out before the storm.

    For what it's worth, you can use a 10 ml sample and each drop is worth 25 instead of 10. If you don't have that footnote in your test directions, I can find the link for you. Who cares if it's 675, 700, or 680? When we're that high, +/- 25 is good enough. And yes, a speedstir is a godsend for CH. Once it goes purple, cycle it again with no drops. A lot of time it will go blue. But your wrist can't keep up that pace for that long, guaranteed.
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    Re: Incorrect CH results

    Jim,

    All of Jason's points are valid. All these values (pH, Water Temp, CH, CYA, Salt, Borate and TA) are all part of CSI (Calcite Saturation Index). You can balance your CSI by compensating your CH by adjusting your TA and pH. I wouldn't waste your money on a calcium sequestrant. I would do like some on here have done which is use the current rain fail to offset a partial drain (using this water to irrigate something) or at somepoint do a Reverse Osmosis Treatment on your pool water which is available in your region.

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    Re: Incorrect CH results

    Jason, Richard, and Sal,

    Thanks for all of the great suggestions. I've already ordered SpeedStir, and will probably pursue the R/O option.

    Jim
    18 x 28 with 8x8 Spa with Vanishing Edge Dam wall, Pentair 4 x 160 & 2 Whisperflo, Badu Swimjet SuperSport, Pentair 400Kbtu Minimax, 80sqft DE CAT 1000 PH Controller with Stenner Pump/Tank combo

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    Re: Incorrect CH results

    Just a follow-up to close the loop on this. I purchased the SpeedStir from Taylor, and it confirmed the 680 CH reading. My tap water CH measured 220. Quick drain, refill, and startup, and the water is crystal clear again.
    18 x 28 with 8x8 Spa with Vanishing Edge Dam wall, Pentair 4 x 160 & 2 Whisperflo, Badu Swimjet SuperSport, Pentair 400Kbtu Minimax, 80sqft DE CAT 1000 PH Controller with Stenner Pump/Tank combo

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    phalcon51's Avatar
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    Re: Incorrect CH results

    Quote Originally Posted by JasonLion
    When the test sample turns purple it is called a floating end point. You may want to consider getting a magnetic stirrer. They help avoid floating end points and greatly speed up the process of testing high CH levels.
    Hmmm, I think I may have been doing it wrong, too, and I just added some calcium chloride to try to bring it up to 300 ppm. How blue should the sample get? I have a magnetic stirrer and I added drops till the color changed, added a few more and it didn't seem to make it any bluer so I stopped. The color was kind of a very pale purpley-blue, not nearly as intense as the red it was to start with. Should I have kept adding more drops? Should it change to a definite, intense blue? I think I might see a partial drain in my future...

    Gary
    26,200 gal. 35' x 16' Plaster IGP (50 yrs. old), Hayward 48 sq. ft. DE filter, Hayward EcoStar VS pump, Intellichlor IC-40 SWCG, The Pool Cleaner 4X suction, Pool Skim and Pool Devil skimmers. Re-plastered Sept. 2010.

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    Re: Incorrect CH results

    Quote Originally Posted by phalcon51
    Quote Originally Posted by JasonLion
    When the test sample turns purple it is called a floating end point. You may want to consider getting a magnetic stirrer. They help avoid floating end points and greatly speed up the process of testing high CH levels.
    Hmmm, I think I may have been doing it wrong, too, and I just added some calcium chloride to try to bring it up to 300 ppm. How blue should the sample get? I have a magnetic stirrer and I added drops till the color changed, added a few more and it didn't seem to make it any bluer so I stopped. The color was kind of a very pale purpley-blue, not nearly as intense as the red it was to start with. Should I have kept adding more drops? Should it change to a definite, intense blue? I think I might see a partial drain in my future...

    Gary
    Gary, Taylor has a selection of videos of test procedures including one with floating end point: http://www.taylortechnologies.com/produ ... deshow.asp
    (Select "Pool/Spa", then scroll down to "General Test Interferences:" , then select "Calcium Hardness Test".)

    Also, do yourself a huge favor and get the Speed Stir! Got mine from Dave at TFTestKits.Net. I would not want to test my CH without it!
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    Mod Squad Bama Rambler's Avatar
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    Re: Incorrect CH results

    Once it stops changing color you stop and don't count any drops that didn't make a change.

    Since you have a magnetic stirrer the test is a lot easier to run. You still need to wait a few seconds between each drop to ensure a good result. If you rapid fire the drops into the sample you'll overshoot the number a good bit.
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    Re: Incorrect CH results

    Yeah, I've got the Speed Stirrer. So, regardless of the color/shade/intensity of blue you stop after no further change within a few drops?

    I'll check out those videos now, too.

    Thanks,

    Gary
    26,200 gal. 35' x 16' Plaster IGP (50 yrs. old), Hayward 48 sq. ft. DE filter, Hayward EcoStar VS pump, Intellichlor IC-40 SWCG, The Pool Cleaner 4X suction, Pool Skim and Pool Devil skimmers. Re-plastered Sept. 2010.

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    JasonLion's Avatar
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    Re: Incorrect CH results

    Yes, anything in the blue family that stays the same when you add another drop is the end, and the final drop doesn't count.

    I have never seen the particular blue that Taylor shows in their video, yet others say that their test is always that color. The blue can vary quite a bit. As long as there isn't any red in it and it stays the same after another drop you are done.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  12. Back To Top    #12

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    Re: Incorrect CH results

    I find that adding some drops of titrant first (and counting those drops in the final count), as is done to avoid a fading endpoint, helps make the final blue more distinct, at least for my pool.
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    Re: Incorrect CH results

    Quote Originally Posted by chem geek
    I find that adding some drops of titrant first (and counting those drops in the final count), as is done to avoid a fading endpoint, helps make the final blue more distinct, at least for my pool.
    +1
    20K gal IG plaster pool, Manually chlorinated with 6% bleach, 1.5 HP Sta-Rite Dura-Glas II pump, Pentair FNS Plus 48 DE filter, Polaris 280

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