My leak detector worked

Today a pipe connected to my hot water heater started leaking. I installed the thing five years ago but it decided to leak today. I would not have known except the water in my reef tank started to get low even though I have an ATO that is gravity fed. Under my hot water tank I installed a DIY water shut off in case of a leak and it worked well. It uses a regular GFCI outlet. I installed an electric valve in the pipe that feeds the hot water tank. That valve is plugged into a GFCI so that if the GFCI trips, the water valve shuts off. I plug a wire into the GFCI where I only have the neutral wire and ground wire connected with nothing on the hot prong. The ends of that wire are under the hot water tank. If that wire gets wet, the GFCI trips off shutting water off to the hot water tank so I don't flood my house. The ATO for my tank is also on that line so the water to the tank stopped notifying me of the leak. I have the same system under my reef tank that shuts off the pumps if there is a leak. I love technology.