An overflow or a leak from an aquarium or it's equipment can cause a huge mess if not caught right away. The Watchdog is a stand alone leak detection alarm that will give a very loud audible alarm in the event water comes in contact with its sensor pads. It is extremely sensitive and we have found they even work with RODI water. The Watchdog monitor is small enough to slip between sumps and stands, or the wired sensor can be placed in even tighter locations. A single 9V battery (not included) will keep the Watchdog running for up to 24 months, standing by to alert you of the smallest drop of water that comes in contact with its sensor. The minimal investment in a Watchdog Leak Detector can save hundreds if not thousands in damages.