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Thread: pH meter issues . . .

  1. #17
    flasker's Avatar
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    What's your pH readings when you measure pH solutions 4.0, 7.0 and 10.0 ? If the readings are quite different then your pH meter could be wrong.

    As long as you don't pump CO2 under pressure into water, water absorb CO2 slowly. Tap water (pH ~ 7.5 - 8.0, basic) absorbs fast and more CO2 than distilled water. Measure pH of a cup of tap water, measure again after an hour you won't see any different (I bet).

  2. #18
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    Quote Originally Posted by flasker View Post
    What's your pH readings when you measure pH solutions 4.0, 7.0 and 10.0 ? If the readings are quite different then your pH meter could be wrong.

    As long as you don't pump CO2 under pressure into water, water absorb CO2 slowly. Tap water (pH ~ 7.5 - 8.0, basic) absorbs fast and more CO2 than distilled water. Measure pH of a cup of tap water, measure again after an hour you won't see any different (I bet).
    Within the course of a few hours, a beaker of freshly-distilled water can easily drop from pH 7.0 to as low as 5.8; and I had mentioned the issue with the solutions earlier in the thread.

    It's all academic; I put in an order for a new meter . . .
    “Sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo . . ."

    -- Galileo "Biff" Galilei

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    Quote Originally Posted by BigBella View Post
    I realize what you're saying; but my first thought was that the batch of testing media was simply off; and why it was a sudden problem was also a bit of a mystery, since the probe is waterproof and the o-rings perfectly intact and lubricated. Also, I was generally using steam distilled water, though had some deionized on hand -- which also registered pH 7.0 . . .
    Sorry, I wasn't trying to 'teach grandma to suck eggs'... might me useful information for other though, who naturally assume that demineralised water must be pH 7.0

  4. #20
    BigBella's Avatar
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    Quote Originally Posted by mobile View Post
    Sorry, I wasn't trying to 'teach grandma to suck eggs'... might me useful information for other though, who naturally assume that demineralised water must be pH 7.0
    No, that wasn't my thought at all; and thanks for the input. The manufacturer, HM Digital, is going to take care of it. Apparently there were some "issues" with a batch of their replacement probes . . .
    “Sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo . . ."

    -- Galileo "Biff" Galilei

  5. #21
    i dont do pots. amphirion's Avatar
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    someone failed QC....
    " You keep using that word. I do not think it means what you think it means." -Inigo Montoya
    +growlist
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  6. #22
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    I got a ph probe, it arrived dry and the cap never stays full of fluid more than a day. Manual says "keep probe wet", it could be a full time job making sure that had water in it...

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