alum tank refurbishing

[DRE]

I just had a couple of AL tanks refurbished at All Safe - I got rid of old paint jobs and now have a brand new brushed aluminium look on those tanks.
The reason I did this is to not have any paint strip off UW and cause pollution (especially in fresh water caves as they are our drinking supply).
BTW, contrary to popular belief you don't need any finish an AL tanks for longevity or protection...

[Punky]

Just out of curiosity why do you say that? Al does not rust like steel but is still suseptible to corrosion.

[DRE]

It is susceptible to corrosion, true, but what I'm more worried about is 1) internal corrosion through moist gas, which you can catch by doing a visual, and 2) the use of dissimilar metals, such as putting a SS clamp on an AL tank (I personally always put a rubber band underneath). Granted, I don't dive a whole lot of saltwater, where it might be more of an issue, but I've never seen an AL corrode on the outside from use in fresh water.
I'd personally be more worried about polluting the water supply from paint (every little bit helps!) than the remote chance of external corrosion on my tanks. Also, in some of the more popular caves you can find paint traced on the cave walls from being hit by painted AL cylinders - one more reason not to have any paint whatsoever...