holy shit, make sure you follow the salt test instructions from the herfers guide to calibrate these things... I did the salt test twice and both times i got a 6 off reading, but i struck me as odd when i calibrated a second hydrometer and it read 6-7 off as well... plus, i noticed my RP i smoked earlier was a little dry... went back and followed the exact instructions to calibrate and the damn thing is only 1% off... somehow my careless calibrations gave me a horribly wrong result.