> "Gennette, Bruce" wrote:
> >
> > Continuous pH is impossible.  Measurement works by comparing the effect
> of a
> > known pH liquid on a specially coated electrode (reference) with the
> effect
> > of an unknown pH liquid on the surfaces (note the s at the end) of a
> special
> > type of glass bulb passed into an electrode identical to the reference.
> >
[snip]

> Damon Hopkins replied
> There are plenty of continuous PH monitors around for that are used in
> fish tanks. Usually they are used in connection with a calcium reactor
> they monitor the PH of the tank and adjust the amount of calcium reactor
> effluent accordingly. They do need to be calibrated on occasion (I think
> like once every month or two)
>
Of course, if you have ever left your pH probe in your saltwater
tank for any length of time, you'd find it was impossible to
recalibrate.    I know this from personal experience. They
tend to last around 8 months or so. I have never had one
last more than one year.

Keep in mind this will vary with the quality of the probe. I finally
tired of replacing the $50 PinPoint probe twice a year. I store my probe
in an "electrode storage solution" from Hach.


Phil Eisermann
H:(440) 284-3787 (mazer@ix.netcom.com)
O:(440) 329-4680 (peiserma@ridgid.com)