I've got a set of EC and pH water sensors that need to sit in the same batch of water / capture values real-time for a Arduino project.
However my sensors cancel each other out when both are submerged cause it's creating a circuit in said water. So I've been trying to utilize these MOSFETs (JEDEC TO-220AB - RFP30N06LEs) to turn power on and off (sequentially) between both sensors and capture their values.
As a test, I've setup two MOSFETs (one for positive, one for ground lines of sensor) and have turned off one sensor, while leaving the other sensor turned on. However even though one sensor is off, I'm still getting a circuit between sensors while both are submerged. If I remove the ground and positive from said MOSFETs, indeed the circuit in the water goes away and my on sensor begins reading correctly.
As results of the above test, I think its safe to assume there is a small current leak from the MOSFETs that is only really apparent when measuring a highly conductive medium such as water.
I've created a video to outline the issue a little quicker:
Does anyone have any advice on the best approach to completely kill a current to a sensor within in a conductive medium like water? Are MOSFETs indeed the correct way to go? Any advice would be greatly appreciated!