Canyon trail 33 FRET grey water issue

[Vetters2]

Good evening. New here and new to gulfstream campers. I just purchased a 2015 canyon trail 33FRET, was running water in the the sinks to flush system, grey valve is open, but get very little water running through hose to sewer? The valve handle doesnt apear to open as far as the black tank does, additionally, according to my tank monitor tjere is a 2nd grey tank that shows full? My kitchen sink wont drain now yet the bathroom sink and shower drain fine?? Is there a 2nd valve im.missing? Sorry for the long post..

Chris

[Vetters2]

Figured it out. There is a 2nd grey tank and the valve for it is just in front of the wheels.in the kitchen slideout. Black handle black frame no markings and hard to see. Pulled handle and all is good.