This is no schematic or anything, just a very simple prototype drawing. All three switches will be off when they float. So it will only be a complete circuit when the water is not lifting any of the three floats.
Note: I will also having timing fail safes, this is just the float switch circuit.
Code:
String 3 sensors together, 2 low one high, in series.
If one switches, circuit is broken. Pump will only fill if 5v input detected.
----------------------------------------top of tank
----------------------------------------------------- <-- +5v
| high-switch--------------- --> input_pin
| |
| |
| |
---low-switch___low-switch____|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~water level