Forces only one pump to be active at a time, to avoid the sudden inrush current browning out the Pi or causing weirdness when multiple pumps fire and drop the voltage.
Note, this is all included in #5 which has an additional fix so that it doesn't free-run the pump and cause water chaos. This probably doesn't need merging separately.
Forces only one pump to be active at a time, to avoid the sudden inrush current browning out the Pi or causing weirdness when multiple pumps fire and drop the voltage.