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either my ph meter is bad or...

Posted by hairmetal4ever Z7 MD (My Page) on
Tue, Apr 1, 14 at 9:23

OK, so I have a Rapidtest pH meter. As I have said before, it rarely works in a soilless mix, but I can get a reading if I take a handful and compress it around the metal tip.

My 5-1-1 is reading between 7.8 and 8.4 - this CANNOT be right, can it? I put half the recommended lime (since I used MG instead of pure peat). The MG itself is 6.5, pine fines are about 5ish from what I understand (I will open my remaining un-altered bag of pine fines and test it today) so unless I got some mutant super-concentrated lime somehow, something isn't correct...has anyone else experienced this? Heck, even PURE lime isn't much above the upper 8's, is it?

Follow-Up Postings:

RE: either my ph meter is bad or...

  • Posted by nil13 z21 L.A., CA (Mt. Wa (My Page) on
    Tue, Apr 1, 14 at 11:09

The only pH meters I have ever trusted are the lab ones with a glass probe. The metal ones have to be cleaned before every use with steel wool or a scotchbrite pad in order to remove oxidation.

RE: either my ph meter is bad or...

Would the oxidation cause a false reading, though, or just NO reading?

RE: either my ph meter is bad or...

I took some steel wool to it. Still weird. The straight pine fines read 7.5, the MG mix about the same. Even straight household vinegar is reading 5.6 and should be 2.47 IIRC.

I think it is way off.

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