OK, so.. Make sure you dump the whole contents of the box out and find the weighted cone thing. In the diagram it is part 7313078.
Like a dummy I missed this the first time I set it up, and it kiiind of worked. The down-tube water level was below the surface so I figured that's just how it worked. Then I found the extra part. After putting it where it's supposed to be, the water level in the down tube is MUCH lower, and it's sipping the water's surface like a champion.
I'm mostly writing this review to provide that information if someone sets this thing up, and it doesn't seem like it's working quite right. Also note that the U tube slides in and out so you can get it set up at the right height.
Seems to have more vertical water level tolerance than a lot of skimmers, if you have a lot of evaporation and don't have a sump - and if you're looking for this, you probably don't.
Really nice cannister-integrated tank upgrade to eliminate film and help with oxygen transfer. The design is also really cool from an engineering perspective, so if you like that, get this.