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Re: Aquatic Plants Digest V4 #286

In a message dated 5/16/2000 00:52:45 Pacific Daylight Time, 
Aquatic-Plants-Owner at actwin_com writes:

> My pinpoint pH probe arrived today and there's no directions for 
>  it.  There are directions on the calibration packets that read, "Immerese 
>  probe into solution."  Ummm...ok....so do it before I connect the probe to 
>  the controller or after?  How long is it supposed to say immersed?  How 
>  often will I need to re-calibrate?  I got packets of 4.000 and 7.000. I 
>  assumed this is what I needed after reading posts.
I use a Coralife pen probe, and it has calibration screws on top of the pen.  
To calibrate, first rinse the pen well and gently shake.  Then, immerse in 
the 7.000 solution.  There should be a 7.0 calibration screw on the 
instrument somewhere.  Let the probe settle into the solution for about 60 
seconds, and then adjust the screw until the pen reads 7.00 (whatever the 
resolution is).  Rinse, gently shake dry, and immerse in the 4.000 solution, 
and adjust that screw as well.  You'll have to go back and forth a few times, 
since adjusting one setting has a slight effect on the other setting.  After 
3 or 4 adjustments, the instrument SHOULD read 4.00 and 7.00 when in the 
appropriate solutions.  My pen doesn't hold its calibration precisely, and 
tends to drift a slight bit over a period of months, so be sure to re-check 
the calibration once every month or so until all components age and settle 
into their long-term values.  After that (about 6 months or so), the pen 
should hold its calibration for extended periods of time.