🚀 go-pugleaf

I would like to build a solid state device that would turn off a water
pump in my aquarium if the water level drops  below a certain level.
I am willing to look at prefabricated stuff but would prefer to build it
my self.
I would like to put the level sensor on the prefilter which hangs over 
the back of the tank and the rest of circuit in the cabinet below the tank.
The reason for the circuit is mostly to save the pump, which relys on water 
for lubrication, shoud it start to suck air.

Many thanks in advance!!!
Rich
p.s. email or news network....I read them both.