Fuel/water separator filter turning black

[Lonestar10]

bio diesel has more lubricity than regular diesel which is why it tends to run better. the downside its more prone to algae and gelling but with proper maintenance and setups neither are really an issue.

i run enough fuel not to worry bout algae and always fill to the brim now with the new light ass t680 "31000" empty full of fuel.

as far as gelling i have heated davco and fox heaters in the fuel tanks and an apu to keep all 3 warm 24/7