Hello Jack,

A 2.5mS swing is equivalent to a 1.001 SG swing which is an unnoticeable change in a reef.
Specific Gravity (SG) is the standard measurement used for reef tanks. Some use the PPT measurement too.


For example, a +/- deviation of 2.5mS is like having a change from 31.8ppt(1.024 SG) to 33.2ppt (1.025 SG); which does not negatively impact a reef tank.

If you want to trigger an alarm at a 1.32ppt (1.001 SG) +/- change, set the max deviation to 2.5mS.