I have a 90 gallon Northern Tool/RDS aluminum aux fuel tank on '06 PSD. I run all my fuel through this tank before it goes into the main OEM tank. Between the two tanks, I have a 3 micron water separator filter setup.
Except on long trips, I don't fill the aux fuel tank nor keep it full. But having all the fuel go through the aux fuel tank and then 3 micron filter into the main tank, prevents algae buildup or at least filters it out before it gets to the main tank. It's also far easier to drain the WS filter vs the OEM HFCM drain.
It also helps that I regularly run Bio in my truck. Bio keeps the fuel system clean.
Good luck.
Al