I don't know what you're talking about - nothing in that thread contradicts what I'm saying.this has been stated previously, @Randy Holmes-Farley posted this...
Hanna Salinity Tester - first impressions
Then 1 ( or both) of Your calibration fluids is not good. Just decide Yourself which one You are going to use as a reference. Or get a chep scale for 1/100 gram and make Your own fluid.www.reef2reef.com
The primary reason people have issues with the Hanna salinity checker is the same reason people get weird readings out of the Apex salinity probes - its because they measure conductivity - and use it as a proxy for salinity - but there are things in a reef tank that can affect salinity.
I'm not talking about contaminants (like Randy is refuting) - I'm talking about pumps and heaters and uv sterilizers and all sorts of other things that induce transient current in salt water.
Some tanks you can stick a conductivity probe in the tank and get one reading, transfer some water to a cup - and get a very different reading.