The Leakalyzer enables you to quickly determine if a pool is losing water, and how much water it's losing. This super sensitive device measures water level changes to the 10,000th of an inch, and tracks these changes in real time on a digital graph. Watching this real-time data enables you to identify leaks in as little as 5-10 minutes. In fact, the Leakalyzer is so sensitive that water loss of less than a gallon from a 20ft. x 40ft. pool is readily indicated.