Mercedes Benz repair: 1984 300D Fuel Tank, fuel filter replacement, biobor

Question
I made a bad batch of bio-diesel, and I need to access the fuel tank to clean it out.  My plan is to simply pump out all of the bad fuel and particulates, flush the lines, and add good fuel.  How do I get to the tank?  Can I get to the immersion tube transmitter to see down into the tank with a flashlight?

Answer
The fuel tank needs to be removed and cleaned.
These links should help:

Algae/Fungus fixation...
http://www.mercedesshop.com/shopforum/showthread.php3?t=138733

240D fuel tank removal and cleaning
Good for any W123 sedan.
http://www.mercedesshop.com/shopforum/showthread.php3?p=813925#post813925

Fixing or Replacing that Annoying Fuel Sender
http://www.diymbrepair.com/Sender/

300SD Fuel Filter Replacement Instructions
http://www.mercedesshop.com/shopforum/showthread.php3?t=105344

Biobor, what is it, why do I need it?
http://www.mercedesshop.com/shopforum/showthread.php3?p=723857#post723857

Filters, Fungus, Biocide, etc.
http://www.mercedesshop.com/shopforum/showthread.php3?p=823378#post823378

Algae Clogged Filter Pic StarTron WORKS !
http://www.mercedesshop.com/shopforum/showthread.php3?t=138728

Biodiesel and WVO - SVO links thread.
http://www.mercedesshop.com/shopforum/showthread.php3?t=111689