refractometer tool

[bpeer]

Looking for clarification.  I just tripped over this during my brew session today.  I use a refractometer and have calibrated it in the program.  I had thought the calibration was for the conversion to SG.  But I was in the tool and entered my brix reading and noted that the plato reading (unfermented wort) was different.  I double checked that brix and plato were for practical purposes the same. So I wondered why the difference?

Searching this site it appears that the calibration takes into account differences between sugar water and wort?
So when I enter my OG into the program I should be using the corrected plato?

If this is the case, that will help my low efficiencies I've been trying to resolve.

Thank you,
Brad Peer

[BeerSmith]

Hi,
  Yes you should be using the corrected plato.  Refractometers are calibrated for plain water, so when you measure wort it requires adjustment which is what the calibration and refractometer tool do for you.

Cheers,
Brad