Aquacontroller Pro Temp Probe Issues

[original-reefland]

I have an Aquacontroller Pro that I have been using for about 2 weeks now. (Unit is used but held in storage most of the time, everything stored in orginal boxes, temp probe was stored dry).

The night I installed it the temperature probe was right on within .5 degrees F to my two other digital temperature probes I already have. Each of these other probes are used to control my heaters and they are within .3 degrees F of each other at all times.

The problem I'm having with the aquacontroller Pro and its probe is that it has since started to bounce all over the place. It is always reading a much lower value than my other probes but not a constant lower value -- sometimes its 2 degrees under, sometimes 5 degrees. I've seen it off by as much as 8 degrees and these ranges fluctuate on the order of half-hour or so.

Minute by minute it seems stable, but when temps are plotted over the day, the temp is all over the chart up and down. Yet the other temperature probes show a solid bell curve of normal daytime temps based on lighting heating the water. I have about 200 gallons of water volume. That amount of water does not change temperature rapidly.

I'm at a loss how to troubleshoot this. It's the only probe being used at the moment, the probe wires are not laying on or crosssing over any other wires. The probe is only submerged about half-way.

Yesterday was rather warm and the tank temperature reached 87*F yet the Aquacontroller showed only 82*F. The programming to kill the lights obviously never happened.

Suggestions?

 

[clp]

Any nicks/cuts in the temperature probe wire? Any corrosion on the connector? If not one of these problems, then I suspect that some radiate electrical EMI is causing the problem. Set the log interval on the controller to every 1 minute. Graph the temperature and see if there is a correlation with some device being on/off. It is likely to be a very electrically noisey electronic ballast, or an improperly grounded hood.

Curt

 

[original-reefland]

I'll try your suggestions. I inspected the wire and connection, looks perfect.

As a FYI - I don't have any electronic ballast. And the lighting hood is not resting on the tank. It is an AB Aquaspace unit suspended from the ceiling about 12 inches above the tank water. Nothing from the lighting touches the tank. These lights are on a different circuit.

I have three dedicated electrical circuits for the tank, the only other device pluged into the circuit used by the Aquacontroller is a Tunze 6100 pump & Controller. I assume they are not known to be noisy.

 

[original-reefland]

I noticed an interesting observation last night. Just me touching the probe wire near the Aquacontroller Pro was enough to change the temperature reading (it dropped by about 5 degrees). I did not bend or wiggle the wire, simply held onto it for a few seconds. Is that normal?

Then, instead of having the probe just dangle in the water, last night I took a piece of styrofoam and made some holes for the probes. I disconnected the probe, place the styrofoam to float in the sump and when I hooked it up again the temperature reading was perfect to my other two probes. Over several hours until this morning it was very stable, staying slightly above the other two probes but close enough.

Not sure why this would make it act differently, be interesting to see if this makes a difference long term.

 

[clp]

It sounds like the temp connector is not making good connection for some reason. Perhaps the internal connector housing is cracked?

Curt