Float (level) Switches
Float (level) switches are heavy duty, water tight and weighted for tank suspension.
This type opens a solenoid valve to fill more water in the tank when it is low and to protect the pump from running dry.
The level switch should just add enough water to keep the pump running and not fill the tank.
There must be room left in the tank for the water returning from the benches, to keep the tank from overflowing.
The level can be adjusted by grower and is very reliable.