I had considered an inline filter arrangement. If one chose to go that route I'd use two filter assemblies in parallel with block/bleed valves allowing one to switch out filters without shutting the system down. Also providing small vent/fill connections allowing one to purge the air from the replaced filter to keep air out or the system. Would also need gauges to monitor the pressure drop across the each filter. Main problem I see is the decreasing efficiency of the system as the filters begin to plug - have to weigh that against the pump life without filters. Anyone have experience with this approach? $1600 for new pumps on a new geo-system kills cost savings for this year!