Have to agree the Instructions on the Priming are not terribly clear at all.
Here's what I do with my CF1200, once I've taken it apart and cleaned it, I then replace the Cannister Lid, place the Inlet Hose back onto the Inlet Side of the Filter, then I get a piece of the Tubing that goes from the Tank to the Filter,
(You will probably have some left, if you have had to shorten the Tubing from your Tank to your Filter),
Place the spare piece of Tubing onto the Outlet Side of the Filter, open the tap on the Inlet Side then Suck, this will then start to syphon water from the Tank to the Filter, once the Filter is full, I turn the Inlet Tap off replace the hosing on the Outlet side of the Filter turn both the Taps on, then turn the Filter on.
I found this the simplest way to get the Filter Primed :bounce:
I run Ehiem Substrat Pro in the 2 Bottom Trays, the Filter Wool in the Top Tray.
Throw out the Bio Balls if your Filter came with them, your far better to use Ceramic Noodles.