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Re: Pinpoint problems -- or Calibrating one's patience

Cavan has two problems with his New Pinpoint pH monitor. 
One is it doesn;t work correctly with the lights on, the
other is that it seems slow to settle on a reading.  He
said, in part:

> It will start out at maybe 5.5 or so and
> initially rises quickly.  Then the upward change slows
> way down.  It will go
> 6.50-6.51-6.50-6.51-6.52-6.51-6.52-6.53 and so forth. 
> This takes around 5 minutes. 

>  If it
> isn't in constant use, do you still have to calibrate
> every month?  

Working backwords through the problems and questions, I
think you need to calibrate every month or so and more
often when the probe is old than when it is new.  The
calibrations sorta wears off due to a number of factors,
changes in temperature affect the electronics and physical
adjusters, the chems in the probe alter over time -- it
doesn't matter if the probe is active or not.

I don't think that 5 or 10 minutes to settle down is
abnormal for pH monitors like this one that are relatively
inexpensive, and attempt to resolve down to 0.01 units. 
The older the probe gets, the longer it may take to settle
down on a reading until it might not settle at all, which
you will see when you try to calibrate it and the
calibration just won't take.  Then you buy a new probe.

But yes, wait a little while to take a reading.

Just curious about your lights, whose ballast are you
using, are the power wires wrapped with a ground wire which
is also connected to the refelctor and the ballast casing? 
You probably have tried these things already -- some
ballasts just emit a lot of radio waves and/or dump a lot
of harmonics on the power lines.

The Pinpoints are a bit slow, but I find them reliable,
reasonably priced, and consistent.  Usually, when I
calibrate each month, I find that the setting is pretty
much okay without adjustment.

Good luck,
Scott H.

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