About six weeks out of the year, I run a ductile iron job in one of my lathes. The rest of the year, it's usually running 6061 aluminum. Do any of you have suggestions on how to best maintain my coolant with this mix of materials? I would like to filter out the fines in some way because I have noticed some black debris on the ID grooves of the aluminum parts. Continuous filter? Filter all the coolant and clean the sump once I'm done running iron? Toss the coolant after running iron? Magnets in the sump to catch all the fines? I'm hoping someone else regularly runs a mix of iron and has this figured out.