The relation being marine water with high mineral content thus having magnetic values potentially not effecting the lab grade hydrometers but refractometers. I also have no awarenes on how the illusion of light as a resolution of measurement through a vacuum with gravitional pulls I'm sure being stronger at different water temps. Next we will test if north east south west effects the sg in refractometery. Lol I'm sure it doesn't effect it much and the screw really just being easy to uncalibrated is the case. But I'm not doubting there is loads more to it we don't know. Allright?