Very serious. I nearly lost my system during an electrical fire. A reactor split a seam, sprayed water on a socket (which was neatly tucked under the tank where water couldn't get on it), and it sparked a fire. Small stuff really. A shorted, and melted 1000W ballast power cord flamed up right under one of my return lines. It charred the line and looks like it came very close to igniting. For all the safeguards I had on that system, that could easily have dumped 1000g on the floor. The room was fairly well sealed, but it still could have cause excessive damage, and perhaps a bigger fire. I will NEVER have another tank with holes in it.