[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: pH monitor
To: "plants" <Aquatic-Plants at actwin_com>
Subject: pH Monitor
From: "Chuck Gadd" <cgadd at cfxc_com>
Date: Mon, 22 Jan 2001 00:39:14 -0700
Ok, just purchased a used pH monitor. I have no idea how old the probe is,
won't be surprised or dissapointed if I need to replace it. I'm going to get
some calibration fluids this week. Right now, I've got the probe in my
sump tank, and the meter reading seems to be jumping thru a range of values
from 6.6 to 6.8. I know that the values aren't really usable until I
calibrate, but is the jumping values a sign that the probe is toast? I
did notice that today when doing a water change, the probe reading climbed, as
I'd expect since I add new water into the sump. And by tonight, the values
were back down to the 6.6-6.8 range, so it seems to be functioning somewhat.
What calibration fluids do I need? I see that they sell a 4, 7, and 10.
do I need to be concerned about adding grounding probe? I seem to recall
mentioning that stray voltage from pumps and/or light ballasts could effect
And if I do need to replace the probe, any recommendations on where to find
the best price?
You didn't mention the brand, so I'll guess you have an American Marine unit
(they sell the most). They are good units. Your unit will have 2 point
calibration. You must use a pH 7 solution can use either pH 4 or pH 10 calib.
solution for the other.
Any of the MO houses has the replacement probes at around the same price:
$45-$50. I wouldn't buy a replacement until you calibrate the meter. When you
calibrate a meter, you are calibrating it to the operating characteristics of
the probe, really. A new probe is needed when the meter fails to hold a
calibration and you get wildly fluctuating readings on the meter. It sounds
like your readings are pretty stable, so your probe sounds okay. When a probe
is wasted I usually see at least a .5 pH variance between high and low
readings if it fluctuates quickly, or a stable but ridiculously high or low
reading totally inconsistent with a test kit reading.
Set the probe in your sump with all your equipment running see what your
readings are, then turn all the pumps, etc in the tank off and see if the
readings stay consistent. This will tell you if you have any electrical
interference. Otherwise, you could locate the probe in the tank itself. None
of my tanks are grounded. No electrical interference issues
If you don't have instructions for proper calibration procedure, email me off
list and I'll help you. It is important to do it the right way to get
accurate readings. I do this every couple months to my controllers/monitors.