On the side of your semen tank that little "port" It is suppose to have a little cap over it doesn't it? I think mine did, but when I got it back home the other day after having it filled it didn't have one. There was just a bunch of sticky gunk in the port area. What is that port for anyway? I have never seen my tank being filled. The guys have to take it way in the back of the very large facility so I have no idea what they do or how they fill it. I do know when they bring it back to me it is covered in frost on the outside of the tank usually.