we would live in a much better world if the scale we all used was EC because that's what the tools actually measure. I like the HM Digital unit. Also super important that you not only calibrate, but calibrate using a reference that is close to your target. These meters are not 100% linear so if you calibrate to 1.0 and you are growing some fantastic tomatoes at 3.0, you're not going to be able to accurately measure that big of difference between your calibration point and reality.