I changed my fuel filter after my first tank of homemade BioD and the filter was black. About how many filters am I going to have to go thru until things settle down? At twenty dollars a filter that offsets my savings quite a bit.
Should only be 1 or 2. Keep a spare filter in your truck.
You should not have to change the filter till the next filter change interval. Do change it if you loose fuel pressure.
Black should be normal from regular diesel use. How many miles on the filter?
If you go through more than 2 you will be dropping the tank to see why and removing the mess.
Again a shot of biocide with BioD use will keep expensive problems away.