Quote:
Originally Posted by
HoppingEnt 
Yes the pumps are submersibles as they are contained inside the system, out of site and out of ear shot. I do not promote the use of gravel for Koi ponds. I like plaster, concrete or liner bottoms. The gravity feed for the oxygenator disk connects to the skimmer and all water returns to the main unit via the 4" pipe. The flow rate is dictated by the height of the discarge line for the gavity feed inside the skimmer. The lower the line discharges from within the skimmer below the water line the higher the rate of flow and it can be set up to be adjustable with a sleeve and coupling. Depending on the design, configuaration or application, bottom drains and jets can be connected directly to the system as well. The main unit can house multipal pumps and multiple BioCores if needed or desired.
I would be interested in knowing more about the Nexus system as well. Thanks!