Apex Conductivity Probe - Reliability

cdness · Nov 10, 2013

I have been looking at the Apex Conductivity module to monitor salinity. I was wondering what the reliability is on the readings? Also does anyone have any recommendations on placement to ensure a more accurate reading?

cdness · Nov 12, 2013

So I installed the probe and module late in the evening two days ago... It read a consistent 34.6 - 35.0 until about noon when my lights turned on. Then it slowly dropped WAY low and didn't recover after the lights went out at night. It sat in the single digits until I woke up for the day. Before leaving for work I took the probe out of the water, then placed it back i and shook it a little to "clean it off" even though it wasn't dirty at all. It is now reading 34.6 again and was consistent to the point of checking it now... I wonder if it is going to drop again when the lights come on.

What could be causing the issue? Is it interference from the T-5 lights? Would it be coming through the APEX unit or could it be interference just because they are turned on?

I am questioning the reliability of this module as there is no way I can depend on the readings with it being all over the board.

cdness · Nov 12, 2013

Actinics just turned on and it is sitting at 34.4... I wonder what will happen when the daylights come on...

mike007 · Nov 12, 2013

Is it close to any other probes? Could be as you said stray voltage from lights.

cdness · Nov 13, 2013

Now it held strong the whole day... Maybe it just needed some time to settle in.

RKLion · Nov 14, 2013

Try this, take the probe out and put the probe in a cup of tank water when its fluctuating and see if it returns to normal...Its probably EMI interference. Im going through this BS too.

RKLion · Nov 14, 2013

cdness said:
I have been looking at the Apex Conductivity module to monitor salinity. I was wondering what the reliability is on the readings? Also does anyone have any recommendations on placement to ensure a more accurate reading?

I dont think its a good idea to set an functions based off the readings as it has the ability to randomly fluctuate. It is accurate I find when working properly but I get fluctuations at regular intervals(more or less same time daily and when I move it around it goes down) so I think I have EMI...