@mrlbem: yes and yes to your questions. Just did a WC with 2075 today. Move your outflow below the water level. And yes, it will also work with filter full of water but the initial suction strength will be lower. Physics at work.
@niko: sucking on a spray bar... Sorry, but you just made me laugh
Might take some practice getting all the outflow holes covered
Also, just imagine the size of those lungs. Sucking on the intake might take less practice but I wonder how long will it take with the outflow up in the air
<puts on a serious face>Eheim is doing something during priming that most (normal) people would find counter-intuitive at the first thought. Press the priming button and watch what's happening in your tank. You will see air (and muck) coming out of your intake
. Interesting. Then, where is the water to fill the filter comes from? Outflow
. Full filter or not, with the outflow up in the air, your result will be the same: you are sucking air into the canister. Now Eheim's recommendation to remove the end-cap from the spray bar during priming starts to make some sense. Why did they do it this way? Just think where most people usually put their intake. (hint: suction force generated at the moment of priming into an empty filter is substantially stronger then what's generated by impeller/motor during normal operation).
In any case, I just hope it works for you.
PS: @khanzer22: wet/dry vac on hi on outflow == no fish, no plants, no wood, no stones, no substrate left in the tank. Cool, we just figured out how to fit a 40G breeder into a 2G filter: compaction