Connect two Versatile Filters to get Filtration up to 10,000 gallons and 3,000 gph. Connect one Livingponds Versatile Filter and one Waterfall Filter to get filtration up to 10,000 gallons and up to 10,000 gph flow rate. Round is Better. 30% of a square box filter is simply unused corner space, the other 70% is active at startup.