Don't want to disturb Thomas' thread so post here hehe.
1.5x1.5x1.0 main pond with 1.5x0.4x1.0 filter
Ultrasieve III depicted, directly interfaced with the dirty water chamber via a 110mm female-female unthreaded coupler buried in the cement separator.
There are no valves in this design for simplicity, save for maybe one on the pump outlet to control total flow rate. A standpipe is used to isolate the filter chamber from the rest of the pond for maintenance.