I have two vertical 20# propane tanks. Is there a device that will tell me when the tanks need re-filling? I really don't want to empty them just to know that they need to be re-filled.
My thought is... why pay for 100% refill when the tank is only 70% empty? Get a changeover device and done.
For me personally... I have a tank valve mounted gauge (only rough estimate) that I check once in awhile and when it goes empty I switch tanks. I have a small travel trailer with only one propane tank mounted. A changeover system is easy.