So, I originally was using an instant ocean beam style hydrometer to test salinity. Finding out that it has its inaccuracies, I purchased a refractometer on Amazon along with Brightwells calibration solution. I have been using the refractometer to check the salt water I was purchasing from the LFS and my tank figuring all was well at 33-34 ppm after calibrating before each use to the solutions 35 ppm. I am now making my own saltwater for about 4 months now. I am using the refractometer still, calibrating before each use. Well my tank was not doing that great so I decided that maybe my salt concentration was a bit on the high side since I was mixing to 34 ppm and I decided to lower the salinity in my tank over a few days to 32 ppm. So today I decided to check with my refractometer and my hydrometer because my Kenya tree was all drooped over. Refractometer, calibrated before use, still seams to be 34 ppm even though I had added slowly over the course of 3 days, 2 gallons of RODI. I decided to check with the beam and it is reading 32 ppm....SO now I have no idea which one to trust...I tested several times with the refractometer, checking calibration each time and cleaning the surface with fresh water and I checked with the beam several times and both continue to provide the same results. 34 ppm refractometer and 32ppm on the beam...I guess I might not even be looking this closely if the Kenya tree was not showing distress. For the most part, I think everything else looks ok.