I think I would start by taking a quart sample of the fuel that goes into the truck and let it settle for a few days to a week. If you find magnesol settling, then something is out of whack in your filtering. The best thing I ever did was buy a bag filter housing from Fryer to Fuel and the fuel goes through it twice with a 1 micron nominal filter. The magnesol is supposed to be manufactured in a way that sizes it to a size that filters will catch (I am not sure of the micron size for this).

JM Ellsworth has 1 and 2 micron canister filters that are rated for biodiesel. Keep in mind that a red blood cell is 6-8 microns in diameter.

I guess I really rely on settling to get most of my magnesol out. I also demeth the fuel, let it settle for a few days to a week, then decant, clean the tank, and refill for the magnesol treatment. I am able to use less magnesol to clean it up.