Conductivity probe compatibility

992gnt · Jan 12, 2021

Curious if most (all?) conductivity probes will work with the P4? I have an Atlas Scientific probe (K 0.1) that calibrated fine, and appears to be reading and logging fine, but I am unable to get the sensor alarm to clear ("the measured value has fallen below or exceeded the alarm threshold").

I've tinkered with all the possible settings, and currently everything is back to the defaults. The alarm trips whether the alarm is turned on or off, and trying to clear the notification results in a loss of connection.

I am on firmware 7.18, and just got the right usb cable to do the update, so I plan on doing that this weekend in case that is the issue.

Any thoughts on why this thing would alarm as soon as the sensor is made active?

Gaël · Jan 13, 2021

Hi, K 0.1 is for fresh water.

992gnt · Jan 13, 2021

Hmm, their description calls out both fresh and saltwater. Is the operating range not appropriate? It does seem to be reading correctly, the only issue is the alarm.

Lasse · Jan 13, 2021

This types of alarms is normally caused by a probe that is outside its range. The GHL controller can be set to either fresh or sea water. If you play around with these settings - it maybe work. But i´m not sure

Sincerely Lasse

Member No 1 · Jan 13, 2021

In the description it states that it can be used in fresh or salt water not that it was specifically used to test salt water.
The K 0.1 has a range of 0.07-50,000 uS/cm while the K 1.0 has a range of 5-200,000 uS/cm.
50,000 uS/cm = 50 mS/cm
Saltwater ranges from 46 mS/cm (46,000 uS/cm) to 72 mS/cm (72,000 uS/cm).
So the upper range of the K 0.1 is at or close to the min range for salt water. Maybe that why you are having an issue.
You might need the K 1.0 probe. But I would buy the GHL one just to be sure.
I run my tank at 53 mS/cm.