I have just purchased an expansion box for my PIII Ex running my reef tank. The expansion box is to monitor water in my breeding setup.
I have had the PII Ex (upgraded to PIII Ex) for about 1 year. The initial probes are the same age (except for the Conductivity probe that I replaced 6 months ago because I dropped the old one).
Both the PIII Ex and the expansion box have the following probes
1. Temp
2. Conductivity
3. Redox
4. pH
For setup and testing of the new equipment I placed the probes in the sump next to my existing probes. They are about 5cm apart.
I have just calibrated all of the probes with the same calibration fluids (old and new probes). About 1-2 hours ago.
Calibrated with the following fluids
Ph with ph 7 and ph 9 Tunze use before date 31.08.2011 and 31.07.2011
Cond with 50mS at 25C GHL no use before date
Redox with 220mV at 25C Aquatronica use before date 09/2011
Fluids were at room temp approx 26C
PIII Ex Probe Readings
pH 1 7.89 ADC1 330 ADC2 113
Temp 1 27.7C ADC1 684 ADC2 312
Cond(S) 1 49.6 ADC1 20 ADC2 414
Redox 1 342mV ADC1 451 ADC2 550
Expansion Box Probe Readings
pH 2 8.02 ADC1 440 ADC2 232
Temp 2 29C ADC1 695 ADC2 323
Cond(S) 2 51.1 ADC1 42 ADC2 447
Redox 2 113mV ADC1 430 ADC2 525
Most of the probes produce a similar result (but with quite a bit of variance) and the readings have been fairly stable for about 1 hour, except for the Redox probe.
The Expansion Box Redox just seems very wrong and is falling on Redox 2 over the hour. It is now at 102mV.
What readings should I trust?
Is there anything that anyone can suggest that would account for the differences and what is going on with Redox 2?
Sorry for the essay, but I wanted to get as much info in as I could so that people have the information that is required.
Thanks in Advance
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