Tunze osmolator problems

[Palmer]

There are plenty of ways to test the sensor by simulating a decrease in water level. If you have an in sump skimmer just raise your water level in the skimmer that will decrease the level in the sump. As far as testing the sensor in another artificial way I wouldn't know. I know my first tunze ATO went nuts within a couple of months and they replaced it and I haven't had an issue with it for years.