Monitors on any tank is iffy on RV's. I think you have two tanks, if so there is a device that switchs from one to the other when MT. When it switchs hunt propane. If its a fixed tank about the only thing you can do is getused to how much you use. I have 38 gallons and fill once a year if in warmer weather and hit it twice if in colder times, most of the fills are about 1/2 to 2/3rds.