Re:[compost_tea] Re: DO Meters

From: dkemnitz2000 <dkemnitz2000_at_yahoo.com>
Date: Tue, 23 Dec 2003 03:29:23 -0000

---

Kevin,
i've run BOD and COD on waste water samples on the bench using wet
chemistry years ago. This used to be about the only accurate
affordable method(and lenghthy) of determining small amounts of
available O2 in water. I Don't remember much about the test but these
new instruments are great compared to wet chemistry, IMO. Kevin, I'd
definitely check with the manufacturer about those instruments you
have. Those instruments are measuring 3 or 6 ppm or 20.9 or
whatever. 0.000003 and 0.000006 are not really much different even
though you're needing to know the difference, needing accuracy and
precision. To get this you may need a more precise instrument but
check with mfgr about accuracy and precision on your extech. This
may help clarify things. Dennis




In compost_tea_at_yahoogroups.com, "kevin john richardon" <kmagic_at_b...>
wrote:
> Changing the membrane did help in the device being able to be
calibrated, yet the number reflecting DO in the tea may not be
accurate; tuff to describe the prob with it, Ime not sure I
understand it myself.
>
> I have used three Extech DO meters at the same time, each one
calibrated (reading 20.9 atmospheric O2) then put into the same batch
of tea, and they each read differently, as much as 3.? off!


 

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Received on Mon Dec 22 2003 - 23:12:13 EST

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