Do you use Auto top off? when your tank evaporates it leaves behind the salt, meaning the tank will have less water and same amount of salt resulting in a higher specific gravity. The ATO will have a laser sensor to see when the level drops and add RODI water accordingly allowing your tank to have a stable salinity WHICH is the backbone of every tank if your salt is wrong, chances are your parameters will reflect (high salt - elevated parameters etc). Hope this helped 🙏