2 different Salinity readings

[Bkimberlin14]

I got my water tested yesterday when I was at the lfs and they said it was 1.021 and to top off with some salt water whenever I went to top off again.

I just recalibrated my refractometer with Brightwell calibration fluid and when I tested salinity after calibrating it read 1.024?

Which one should I go with?

 

[landlubber]

assuming the nsw in the brightwell bottle hasn't been contaminated in any way I'd side with the result from the calibrated test. fish stores are busy and offering the service doesn't automatically ensure foolproof results and it takes very little to knock one of these out of tune.
also, it's been pretty obvious in the past when the salinity has slipped in my system as I quickly notice fluctuations in my other parameters as well.