@johnnyfp When first read this I was wondering if the signal would be reflected accurately off the surface. Apparently not. I'm currently using float sensors which gives me full and empty. I would like to get a level sensor that was accurate to a centimeter so that I could measure the rate of fill, too. My current endeavor is to take this tank gauge put eight magnetic switches around it, and a magnet on the wheel inside. The magnetic switches would be connected to an Arduino nano and I could tell where the wheel is. Alas, other projects have higher priority.