2012 ML350 Bluetec 134k miles.

I am seeking advice from someone who has vacuumed some or all of the fluid out of the Adblue DEF tank.

I bought this vehicle about a month ago and I’m trying to learn all I can about it (it’s my first Mercedes). I am not sure if the previous owner has ever removed all the old fluid and refilled (as the maintenance schedule suggests).

I have removed the inner fender and inspected the plumbing to try to determine the best way to remove a hose and insert a suction line into the tank. I’m guessing the stainless clamp around the big rubber hose a few inches above the tank might be a good place to start.

Can anybody confirm or advise a better way?

Thank you.
Tom