Where did the water go?

[hkgar]

The other morning I noticed that my salinity was 0. Of course I rushed down to my sump room and discovered that the sump was virtually empty with only about 1 inch of water on the bottom. Since the salinity monitor only dips into the top 1 inch of water of course it was reading 0. Between 6:10 am and my discovery the level had dropped about 9 inches and lost almost 20 gallons. My only thought is that it siphoned out through the DOS pump. I didn't think that could happen.

A copy of the chart showing the salinity drop is attached.

 

[Sinn Sage]

Without seeing pictures of your setup, I am going to go with that you have a leak between your sump pump and your display tank.

Is it plumbed so that the pump can pump out water during water changes?

The only thing that should be 1" above your sump floor would be your pump suction unless you have some other pipe that goes down that far. I seriously doubt it was your DOS because that is a lot of water to suck through such a small line.

Pics would help