Hello, We have a well. Our pump water tank is wellxtrol made by Amtrol model # wx203. Our pump is a goulds jet pump made by AD Smith corp. When we flush the toilet the tank will go on and off several times with each flush. I turned on the water and went to look at the gauge to see what was going on. The normal state was around 42 lbs. After a while of letting the water run ( I turned the water on low) the gauge eventually went down to 38 and then it quickly went down to 20. When it went down to 20 the pump turned on. The gauge went up to 40 and then the pump stopped. Gauge goes back down to 20 again and the pump starts up and takes it to 40. Apparently the pump isn't filling the tank up all the way all the time, and therefore the pump turns on and off.