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Thread: According to my CYA test I have almost none

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    According to my CYA test I have almost none

    According to my CYA test I have almost none. I can see the black dot with the tube overflowing. According to a very expensive testing machine at the hardware store, my CYA is 20.

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    UnderWaterVanya's Avatar
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    Re: A Better CYA Test Kit?

    Quote Originally Posted by reynolds357
    According to my CYA test I have almost none. I can see the black dot with the tube overflowing. According to a very expensive testing machine at the hardware store, my CYA is 20.
    20 is close to the limit and with +/- 10-15 ppm accuracy clear could be 5-10 and 20 wouldn't be outside possibility.

    Do you have a log of what has been added?


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    Re: A Better CYA Test Kit?

    According to a very expensive testing machine at the hardware store, my CYA is 20.
    How does that very expensive machine work? It probably reads a worthless test strip and gives you a meaningless digital readout. Perhaps it even uses the same turbidity test that you currently use but uses it's electronic "eye" to judge the cloudiness. Either way, those results are usually not as dependable or repeatable as the test you own.
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    Patrick_B's Avatar
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    Re: According to my CYA test I have almost none

    Maybe 20 it the unit's low limit?

    In any case, I would trust your test kit reading. It is accurate.
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    Re: According to my CYA test I have almost none

    Duraleigh, the test uses a chemical reagent inside a sealed vial to which pool water is added. The reagent with added water is shaken and then allowed to sit for 30 seconds. It is shaken again and then sets for another 30 seconds. It is shaken a third time and then put inside a machine which uses an optical eye to read the chemical. It will give you two numbers "CYA" and "CYA corrected for alkalinity." They are never the same but always very close. The CYA test is done as the last test in the comprehensive series of testing. They computer will not do the test unless it has at minimum the Total dissolved solids and the Total Alkalinity number. I have not put anything into my pool in three years that contained CYA until this week. The highest I have ever had was 70. This machine has been consistently reading lower and lower every time I have had water tested for the last three years. This week, I started using tri-chlor again to slowly raise the CYA and to allow me to slowly add some borate without using acid. For the most part, my pool maintenance is Ca-Hypo, Na-Hypo, Borax, MPS on occasion, and muratic acid on very rare occasion. My pool is intentionally loaded with Cu. It has not had any alkalinity increaser added for at least two years (other than Borax)and I have no problem with PH issues.
    Brushpup, I will look at the machines parameters and see if 20 is indeed the low limit. It is possible.
    The machine is certified for testing both well and municipal drinking water.

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    Re: According to my CYA test I have almost none

    That is odd that they have "CYA corrected for alkalinity" since it sounds like they are adding melamine to create a melamine-cyanurate precipitate but they are NOT adding a buffered acid along with that melamine to ensure a low pH that maximizes precipitation so that all of the CYA gets measured. If you don't add buffered acid to ensure a low pH, then you won't get cloudiness and technically melamine-cyanurate in distilled water is soluble up to around 20 ppm so won't cloud the water until that level.

    So perhaps 20 ppm is indeed the lower limit of their test. You can try giving them a sample of tap water and see what they say. If they say 20 ppm, then you know that's a lower limit for their test and it means <= 20 ppm.
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