Posted: 11/12/2014 at 15:30
Design 2 and 3 are far too over the top for domestic use and will be far to complicated unless you have an instrument tech
Design one looks like an off the shelf unit and will be unsightly in most gardens.
There is no sump so any grit will collect around the pumps also with the differing head the pump flow rate will be veritable. Pump selection will be difficult also unless vds's are used.