SRO 5000 Ext Auto Draine Issue

Hello,

I purchased a SRO 5000 ext skimmer this week. The skimmer is located in a cabinet I constructed on the side of my home just behind the tank and is plumbed through the exterior wall into my sump. The cabinet also includes my water change mixing tank, RODI unit and dosing pump, but those facilities should have no bearing on my question.

The skimmer is located at least as high as the highest point of my physical sump (which is several inches above the water line in the sump), but the return line from the skimmer into the sump via a bulkhead is at sump water level.

My installer and I are having a problem in which the auto-drain line seems to be acting as a syphon from the sump when the skimmer pump is not on. Specifically, if the skimmer is not on, the skimmer body fills with water from the sump and then the auto drain is draining water from the skimmer body. This seems odd in that the auto drain is supposed to pull only if the water level in the collection cup rises above the drain line for the auto drain, but the auto drain near the bottom of the skimmer seems to be connected to and pulling water the lower body of the skimmer itself.

This is not an issue if the skimmer is on, but that won't help me in a power outage.

Any thoughts?