Diesel/Bio/SVO and aluminum tanks

I am looking at adding some fuel capacity and considering either an Al tank or plastic tanks in the bed. I haven't found any plastic tanks I like, so that may be a moot point. But I can build a large Al tank for the bed. The question is about compatibility. I have read that SVO and Bio can be problematic in steel tanks, how does this effect Al. Also if I primarily run Bio or SVO in the big AL tank would there be any problems with running regular diesel in the tank as well, say I can't find bio or SVO on a trip.

Thanks with the smog check discussions, crappy ULSD and the price of regular diesel I am considering all options to keep the truck running cleanly, efficiently, affordabley and reliably.