Described herein is technology for, among other things, controlling a pump
submersed in a liquid, where the pump includes a plurality of capacitive
sensors. The capacitive sensors include a first capacitive sensor and a
second capacitive sensor disposed above the first capacitive sensor. The
technology involves sensing liquid levels with the capacitive sensors,
activating the pump after the second capacitive sensor detects the liquid
in a normal mode of operation, deactivating the pump after the first
capacitive sensor no longer detects the liquid in the normal mode of
operation, detecting a failure of one or more capacitive sensors, and
adjusting the operation of the pump to compensate for the failure of the
one or more capacitive sensors.