It's always good to have some liquid in the tank to keep solids of any sort from becoming hard. I have used the Geo Method over the last year and have not had a problem except for faulty sensor reading, which is common. This year I am going to try something different. When I get home I will fill the tank and put some Microbes in it to dissolve all solids that might might be clinging to the probes or walls.
Terry and Carol
Daytona Beach, FL
2013 F150 XLT, SuperCab, Ecoboost
2010 Rockwood 8285WS
2014 - 57; 2015 - 91; 2016 - 171