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Thread: Calcium Hardness Test

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    Calcium Hardness Test

    Just received my TF100 test kit and I seem to have a problem. CH test is at 1000ppm and all other tests are within normal range. Before using the Tf100, one pool store test showed CH at 1100 this was about a month ago. Drained pool about 2ft and refilled had store check again and CH had dropped to 600 using there tests. When I received my test kit three days ago it showed it was at 1000, again I drained approx 2 feet refilled, ran pumps and kept flushing for about nine hours, ran pumps overnight and the TF100 showed CH at 1000. This morning I took a sample to the store and there it came up at 400ppm. Water is crystal clear and the pool is about two years old,12000 gal,crystal stone finnish and Auto pilot SWG. Fill water checks at 100 ppm with the TF-100. Any help would be appreciated!
    12000 Gal Rectangle pool, crystalstone finish, Autopilot sc36 SWG pentair cartridge filter,Polaris 380

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    Re: Calcium Hardness Test

    Wow! That's pretty high.

    First, reread the test instructions and confirm you are doing the test correctly. (Don't mean to sound like a kindergarten teacher but double check)

    Secondly, it sounds like the test has repeatability in that you are consistently getting a similar reading. The exception is the test result of 400...were they using a drops-based test? (Your finger and thumb must be exhausted from counting all those drops)

    Last, I am puzzled. The most obvious answer is that it really is that high. Test your fill water and see what you're putting in....that may help. The CH test in the kit has been perfectly reliable and your kit is among many using the same batch of reagents from Taylor brought in about two weeks ago.

    Some of the real experts may have some insight that I don't have...maybe they'll chime in soon. Meanwhile, post the test from your fill water to see if there's a clue there.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Guest
    How is your pool store testing? If they are using a LaMotte Waterlink Express or LaMotte Waterlink (vials of dry reagents put into a machine to be read after having the water added to them) then the upper limit of testing with that system is about 500 ppm and the test will read low if the calcium hardness is above that. We use such a system at work and LaMotte tech support has told me to do a titration test when calcium is suspected of being high for this reason. I would trust your readings from the TF100.

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    More numbers

    Took another test this AM numbers are:
    FC 10
    CC 0
    PH 7.8
    TA 70
    CH 1000
    CYA 30
    SALT 3260 Added 40 lbs yesterday
    Fill water 100
    Will check with pool store to see what type of test they are using. I went exactly by the instructions on all tests. Ran boost mode last night to bring cl up. Have not added acid yet to bring ph down. Water is crystal clear and no scaling on pool or salt cell. Normally need to add three or four cups of acid every three days to keep ph in check. Appreciate all your help and any suggestions on trying to lower ch. Thank you!
    12000 Gal Rectangle pool, crystalstone finish, Autopilot sc36 SWG pentair cartridge filter,Polaris 380

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    Re: More numbers

    The fill water test would certainly indicate you actually have that much CH in your pool. It cannot get there on it's own so it must have been introduced in the pool as an additive at some point.

    It's reassuring that your water is clear with no sign of scaling......it indicates you have kept all other parameters of your pool under control.

    I only know of two solutions. You can hook up a water softener to your pool to remove the CH or you can drain and refill. If you drained 50% and refilled with 100CH water, you should be somewhere around 600 which is still a little high but out of the "cause for real concern" range. Couple that with some rainwater over the winter and you might get back to the 200-400 ideal range over the winter.

    Your other numbers are decent and it seems you've managed your water very nicely so you could always choose to leave it alone. I would be reluctant to suggest that, however. Scale is a real problem if it appears and you appear to have a big dose of one of the ingredients for it's formation.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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