We filled our fresh water tank for the first time and was wondering how do we know when it's full? I've looked around the forum here and people keep mentioning vents but I looked all under the unit and can't find any. I filled it until it was making some weird gurgling sounds and then got nervous I was going to break something lol (lots of mention on here about the underbelly filling with water when filling tanks). There appears to be a vent hole right beside the fill port. Will water come out of there when it's full?