We get a lot of questions regarding if it is ok to leave various probes submerged in water. There is a short and long answer to the question.
The short answer is yes, you can.
The longer answer is yes, but make sure you know the pros and cons. You can leave any probe submerged in water, in fact, the industrial versions are designed for exactly that. The lab versions are primarily designed for use and then storage, but can also be submerged.
For EC probes, there really isn't anything bad that can happen to them from continuous submersion. There is nothing in their design that will degrade. If you frequently submerge and then remove them, you'll need to ensure they are cleaned and they don't develop calcium/hard water deposits as the water dries. These deposits may not dissolve very easily when the probe goes back in the water and will alter the readings.
For pH and ORP probes, it is best to think of them as disposable. They are inherently designed to slowly degrade. In these types of probes, there is a junction where a solution on the inside of the probe physically touches the water on the outside. Due to this water/water junction, the probes will slowly degrade over time.
Some things that determine how quickly a probe degrades are:
- fast flowing water
- high/low temperatures
- chemicals in the water
To speak specifically of μFire products, if you want to have a probe continuously submerged, the industrial versions are your best bet. You can expect about a year of useful life with regular maintenance and recalibration. The lab versions can also work continuously submerged, but their useful life is significantly shorter, approximately six months.