Keep your refractometer readings accurate!
A refractometer is easily one of the most important tools to have if you own a saltwater tank. Without a refractometer, we would be guessing at how much salt is in the water, and more than likely would not be correct! Even if you have a refractometer, it is only as good as how accurate it is calibrated. BRS Calibration Solutions are made of high purity salts that are precisely mixed for their particular application. 
1.026 or 35ppt