The probe is about a foot deep. The main thing you want to do is keep the probe far away from the chemistry input that way in a bath you have proper mixing. Now, as you see in the pictures we provided, the fluid flows past the probe in a tee and we have the flow going from your wash pump, past the probe, through these isolation valves. We used to dip the probe in the tank but now we provide the flow by a way of a mixing pump.