How do you keep you salinity at a certain level?

[spawn]

The only dislike I have about the newer tunze is that the magnets have a tendency to move easily on their own I think cause over time by ANY minor touch or vibration, I've been trying to get mine back to exactly where it was for a week due to bumping it. I can get it there but then the polarity on the oposing magnets seem to shift a little bit every day. But in terms of stable salinity ATO is a must IMO.