The Aqua C EV180 needs 420 gph - we bought the PanWorld 40PX Ext Water Pump which is 480 gph. Seems to be doing awesome. We are waiting at least a 2-3 week period to see a difference in the microbubbles as it states in the paperwork we got with the EV180 that it will take that long. Be patient - that may be your only prob - let it cycle... ???
