I bought a new diesel can when I bought my tractor. I was using "sta-bul" additive. I like having fuel on hand for the "what if" scenario. Last year I just happen to look in the can while adding the sta-bul before filling it up and I see globs of black stuff rolling around in the bottom of the can. Algae. I had done everything I could do to not have this problem.
Now, I don't store fuel for long, I'm using "stanadine" along with the sta-bul, I'm changing the filter closest to the tank every 100 hrs and look in my can every time I refuel. If it has been sitting for awhile, I use a funnel with a built in filter. It's a pain but keeps the chunks out of the tank. The days of keeping a tank of fuel for years are gone.
One of the things that I have noticed here of late is that stationary diesels for fire pumps and generators tend to use a fuel system that has a return to tank. Since most of these applications are ran for 1/2 hour every other week for maintenance, I wonder if circulating the fuel and stirring things up helps keep the growth at bay? If so, my can in the pump house is the worst way to store it.