go with the DIGI-LAB handheld TTS. I just found that my Refract is off my 5 points. the thing even comes with it on testing sulition. about 90 bucks and well worth it. http://www.jbjlighting.com/sys_digilab_tss.html
how do you know the digital isn't off? :notsure:
not saying you are wrong, but I may need to buy a new salinity tester, and am trying to decide between another refractometer and the digital stuff
Any refractometer worth its weight should be able to be calibrated. A few drops of RO on the lense, calibrate to SG of 1 and you're ready to test again...