If you turn off the circuit breaker to the pool pump, does the SWG turn off? If it does, it seems like the SWG is attached in parallel with the pump at the breaker or attached to the line screws of your timer instead of the load screws. SWGs are meant to be powered only while the pump is powered. While the flow switch for the cell is preventing it from generating chlorine when it shouldn't, you might get longer life from your controller if you attach it so it only turns on while the pump is running.