The level drops past the probes for feeding the cleaner and turns on the feeder unnecesarily.
Most cleaners operate quite hot and evaporation is a big factor.
Put a barrel in the tank, and manually get the level where you want it. Then pull the barrel out, and set the probe so it will add water when the solution drops below this level. Thanks for your reply, Ted. My cleaners are controlled by conductivity probes, and it is the level of the solution that needs to be controlled. Evaporation draws the solution level down so far that the probes are exposed.