Ditto on the above reply. I always drain the canister and then wipe up the remaining diesel and sediment with a lint free cloth, you don't want that crud going to the injection pump when you restart.
Do yourself a favor, snip off a piece of the drain hose from the FF and purchase a 3' section from a local hardware store. Replace 'shorty' and tuck the excess into the frame. The next time you change the filter, untuck your new addition and place the end in a container under the truck. When you loosen the FF cap with the drain valve open, the majority will flow into the container, works great !
Scott W.