I'd say yeah because it's more umm, "organic" than dino diesel. I had some B100 in a spare tank, just a little sloshing around that the pick up could get out. Well it sat for about a month, and when I was able to drain it, the stuff was NASTY. Plus you always can get condensation build up, and that's why you have a fuel drain valve, unlike gas engines where a little water will readily mix with gas and just burn off.

 

Biodiesel will grow algae if it is stored for too long, I have heard various numbers but the consensus is generally longer than 6 months in storage. I have seen first hand B100 stored for up to 9 months and no growth so I guess it depends on conditions.

From the research I have done conventional diesel will grow algae when water is introduced, the algae likes to grow between the water and diesel layer. I have been seeing this more and more with trucks that sit for a period of time. Mine mostly sat with only a few trips to town for 3 months when it developed the algae problem. My moms truck sat for 6 months and developed the same algae problem. You don't necessarily just get water from bad tanks at gas stations, it can form from condensation from heating and cooling especially in damp climates like the midwest.

There are only 2 places in my town to get diesel from, I always fill up at the same place and I have never had a problem until my truck sat for a period of time.

I went and bought 2 extra fuel filters when I bought the bio kleen because I figured I would plug up the filters when I started clearing out the algae. I have put 4,000 miles on the truck since then and I only changed the fuel filter once. I changed the filter at 1500 miles and it didn't look like it needed changed but I did anyway for my own piece of mind. From what I have found the bio kleen dissolves the algae so small it just mixes with the diesel and goes right through the filters and gets burnt up with the diesel.

 

It can't be from fuel sitting in my truck. Lately my truck only gets a full tank a week. There are times I go through a tank and a half a week. At minimum I drive 380 miles per week. I guess the water sitting on the bottom of my fuel bowl could be old. The time I suspect I got bad fuel was mabe 2 months ago, I don't remember exactly. I guess I should drain the fuel bowl at least at every oil change which is almost always under 60 days.