As Thal said unless you are using mixes greater than 40% all regs are ok. And the statement about having to clean them once they've been used with "regular air" whatever that is also is a load of crap. Unless that air is full of oil or other contaminants and then you have even bigger issues to deal with. This is yet again another example of the lack of education in basic Open Water courses. It does not have to be a nitrox course to address these issues. It can be discussed at the same time as when we tell students not to go down to Bubba's fillin station to get their tanks filled. And yes it is also alot of CYA on the part of the manufacturers.