Hey, I didn't know this thread was over here too
Im going to do this same exact thing. Luke and I have been collaborating. Bascially a totally gravity fed filter system, with the deicer propeller pump thinging on the last chamber pushing right back to the pond. Waterfalls and other ammenities would be from other pumps.
The only head pressure on this type of system would be backpressure. If your gravity feed piping is undersized, you would definetly notice it.
Here is my filter system (before deck was added and pumps. The top 3 chambers are each 200 gallon settling chambers. Each connected by a 4" drain to the bottom of the pond. These chambers are all connected to the long chamber which is a horizontal filter chamber. First item in the chamber is 3 rows of black night filter brushes (48 total). Then bird netting as the bio-media. The pump(s) sit in the dry chamber on the right.
To add this new style pump, I would modify this long horizontal chamber to have a 6" pipe boot leaving and going right back to the pond. Then the pump would be mounted on the wet end (inside the filter).
I will be trying this next summer!! If that pump moves 20,000 gallons, even this filter system might be to undersized for it for the gravity flow to settle out enough particles.