Subject: Re: pH Monitor Tips -- What? No Probing Puns?

[Dgrim62 at cs_com]

(snip)
Date: Thu, 8 Aug 2002 13:47:57 -0700 (PDT)
From: "S. Hieber" <shieber at yahoo_com>
Subject: Re: pH Monitor Tips -- What?  No Probing Puns?

Gil (gillmannsf at cswebmail_com) said, in part:

> . . . Today's monitors and probes have a
> temperature sensor included in the probe and the
> correction is done automatically, which is why we don't
> need to worry about this factor.

Wonder why the calibration fluids are marked for temperature.  They
were made for old (type) probes?  They are old fluids? . . .

> They should be
> cleaned regularly, though. (Once a month?) 

That's what my instructions said.


> This is done
> by soaking the probe tip in pH 4.0 buffer for about 30
> minutes. . . 

Not what my instructions said.  Mine said gently glean with and only
with a long bristled toothbrush -- push the end fo the probe straight
into the ends of the bristeles and turn 3 or 4 times.

> 
> I hope this helps demystify monitors and controllers.

Well, it demystified the monitors and controllers, but now I have a few
questions about the instructions ;-)
> 
> 
> 
> The little packets of calibration fluid are the same as
> those in the bottles.  The packets, though, are
> generally a one time use, 

The Pinpoint packets have enough in there to easily submerged the probe
end and that's about all.  I would count on using a packet for just one
calibration.  You can dip right into the packets and successfully
calibrate. 

> while the fluid in the
> bottles can be used for multiple tests.  

You probably don't want to put the probe right into the bottle -- best
to pour bit out into a clean container, no?  So you don't actually
*re*use the fluid but it's still cheaper to buy in "bulk."

Scott H

__________________________________________________
Do You Yahoo!?
(snip)

I have a packet of American Marine pH 7.0 calibration fluid in front of me 
now. The correction table shows you that 77 deg. Farenheit you should adjust 
the monitor to 7.000. The difference in the correction values for higher 
temps (86 DF) is 6.988 or lower temps (68DF) is 7.016 and is so negligible 
why bother, unless your tank is in a greenhouse or a meat locker. My 
Milwaukee instruments controller only goes to one decimal place anyways, and 
American Marine monitors/conrollers only go to two decimal points.

American Marine (pinpoint) units are good, but a PIA to calibrate, meaning 
they take a long time. Milwaukee Instruments units are much easier to 
calibrate. I don't need lab accuracy in my controllers. Very close is just 
fine.
Dave   

 


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