MNScuba.com

Is there any shop around Duluth that does nitrox fills with hyperfiltered air to not contanimate my O2 clean tanks?

Sorry..unless something has recently changed you wont find anyone to do that.  I am pretty sure that Jays shop( Superior Scuba Center) now closed..was the only shop filling Nitrox...and it was not hyper filtered.  I do not know the closest shop that could help you out...

sorry  Good Luck

Deano