I thought about blocking off the slots that allow coolant to return to the tank. Then to build a shallow settling sump and filter arrangement and another pump to then send the collant back via a hose to the main tank.
This return pump could be wired through a relay to be controlled by M8/M9 from the main collant pump circuit. Or, allowed to run a bit longer than M9 with a timer, but would then require logic to keep the pump on after M9 shuts down the main pump..... a latching relay??