Please let me redeem my self , diesel can contain algae.

More exactly, the tank can become coated with algae that can break free when gasoline is added, or even when a constantly run low tank is filled with diesel fuel.

Case in point, my 70's International backhoe ( with a German Neuss engine ) was a contractors main machine when new. At some point it made it's way to the contractors farm as an occasionally used machine. While at the farm it probably was run between 1/4 - 1/2 tank for who knows how long.

I got a hold of it in the mid '00s, did a full service , ran it at 1/4 - 1/2 tank for a year or so. Filled it full for a long job and after a few hours the fuel filters clogged, and continued to clog after changing. Added a clear filter to tank outlet and it clogged pretty rapidly but at least I could see the impending doom.

Seeing the tank was still shedding, pulled it, cut a window and cleaned a lot of junk from the inside. Most of the junk was above the 1/2 tank level, when I ran it at full, the fuel started breaking this loose.

And to show one thing leads to another.. . Pulling the tank gave access to the starter, pulled the starter for an internal inspection ( OK ) , inspected the flywheel ring gear, found it was very worn, pulled engine to change ring gear. While it's out, changed rod and main bearings , valve seals and front and rear crank seal.