I have a JoeTap machine that holds a 2.5 gallon keg. After much R&D, I got it to weigh my kegs properly:
1) 2.5 gallon kegs don't have a tare weight. I simply weighed the keg empty and entered "5.4 lbs" into the Winky app.
2) I filled the keg with my concentrate and water mix.
3) I...