Hello

i have a confusion with calibration equation for the EC-5, because it's not clear for me the way that i should to use it, for example:

you provided this equation: VWC = 10.3 x10-4 * mV - 0.334 for Potting soils, then if with the 2500mV calibration i have an output with ranges between 280mV and 410mV (measurig the output with a multimeter), can resolved like this:

10.3 x10-4 * mV - 0.334
10.3 x10-4 * 280 x10-3 - 0.334= -.3337116
10.3 x10-4 * 334 x10-3 - 0.334= -.3336559
10.3 x10-4 * 410 x10-3 - 0.334= -.3335777
10.3 x10-4 * 1000 x10-3 - 0.334= -.33297 (with 1000mV, that supposed is the maximum output value)

then i wonder, which ones are the values of VWC really?. unless the way to write the formula is: 10.3 x10-4 * (mV - 0.334) then can resolved like this:

10.3 x10-4 * (mV - 0.334)
10.3 x10-4 * (280 x10-3 - 0.334)= -.05562 x10-3
10.3 x10-4 * (334 x10-3 - 0.334)= 0
10.3 x10-4 * (410 x10-3 - 0.334)= .07828 x10-3
10.3 x10-4 * (1000 x10-3 - 0.334)= .68598 x10-3

but, what are these results? if every value lower than 334mV are negative, and it's supposed that the values are in m3(cubic meters), how i should interpret these results?

unless the ways of how it has resolved the formula are wrong, and if that is the case, would appreciate that explain me how i should interpret the formula (with brackets to facilitate understand it) and how interpret the results too.

thanks for your attention.

Hello Virgil, thanks for answer

yes, just the prongs are buried, so i have a wrong measure, right?. ok, i'll test burying completely the sensor, thanks.

but i have a doubt, if i still get negative values with the formula, what means?