Eye opening specific gravity readings.. just received my new Hanna salinity tester and after calibration and taking a few measurements Im shocked at the results, I have a old hydrometer and a refractometer that I have been using for years which seemed accurate enough and for the most part they read practically identical however according to the Hanna my tanks are running 2 ppt low with readings around 32.9 ppt not the 35 ppt my other testers had indicated. My first thought was the Hanna had to be wrong but after referring to IO’s weight to volume ratios and carefully weighing salt and measuring out water to produce a 1.022 sg @ 77 deg calibration solution I’m now realizing my other testers are wrong and I have been running my tanks about 2 ppt lower than I thought

no wonder I had been struggling to get Mg and calcium up! The Hanna is super easy to use and should simplify keeping my parameters in line.