Your CO2 is on and supplying your reactor nicely. Your canister filter (which provides the flow through the reactor) is plugged into a GFCI. While you are out, the GFCI is tripped. You return six hours later and reset the GFCI. What happens?
You realize you should of had your co2 plugged into the GFCI outlet along with the filter. Or for as many times as those GFCI outlets false trip, remove the GFCI and install standard outlet.