Design a sensor to check water movement (make sure powerhead pumps work)

[reivaxy]

And of course adapt the program to check this sensor data.

Random ideas:
IR beam:

• a flap in front of the pump moving water would move a flat piece from between an IR led and its IR Receiver
• when flow stops, the flat piece comes between the IR elements, the receiver no longer gets anything => detection.

Possible issue with stuff blocking the flap (algae, ...). Oh, and also, plastic floats :(

Hall:

• a Hall sensor used to detect pump motor rotation.

Possible issues: may not work for all pumps. Some mecanical failures coud have motor rotating but still not moving water.