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Re: Pinpoint PH Monitors - minor warning
> Date: Tue, 6 Apr 1999 18:12:51 +0100
> From: "A M Moore" <andy at ascot_u-net.com>
> Subject: Pinpoint PH Monitors - minor warning
>
> This may seem obvious, but it has only become apparent to me very recently.
>
> For weeks my PH has been stable at 6.8-6.9, after calibrating my Pinpoint PH
> monitor. Over the past two weeks, I noticed the PH gradually rising to
> around 7.4. At the same time my meter started to show low battery.
>
Note: I use the controller/monitor.
About 6 weeks or so ago I posted something about having 4 dKH and a pH
of 6.8 and my plants weren't doing anything (no pearling by mid- to end
of day). I tested my CO2, found little, so I set my monitor to cut off
CO2 at around 6.3 (which would have otherwise put me in the lethal
range). I determined that something was amiss with my probe. I would
be able to successfully use the 7.0 and 4.0 calibration fluids, but when
I stuck the probe back in - nothing.
> Just got around to putting a new battery in the monitor and immediately the
> PH shows as 6.4.
>
I bought a new probe. My old probe would have read the pH of my water
at 6.3. When I calibrated the new probe and put it in - something like
6.7 or 6.8.
Something else I noticed right before I got the new probe (which was
longer than the original). The monitor would start making this
incessant buzzing sound when the pH of the water approached the point
where it should shut the CO2 off. I found that touching the wire of the
probe would exacerbate the buzzing, or make it stop.
Now that the new probe is in, everything is running smoothly again. I
set my mid-point to be 6.7, and there seems to be the appropriate
amount of CO2 vs KH.
> The moral of the cautionary tale is, if you run your monitor on battery
> only - as soon as you see the low battery indicator, change the battery ! I
> had actually altered my needle-valve slighly to compensate for the high
> readings.
>
> I suppose it also pays to keep a `wet` testkit available as well.
>
I'll be keeping a closer tab on my monitor with my LaMotte CO2 test
kit. I always know my KH is going to be 4, so it makes it easier to do
the math.
--
Kelly Beard, Cat IV (on sabbatical)
President, Allanti Cycling Club
Innovative Computing Corporation