There are many opinions on this subject. A lot of regulators are set up for up to 40%. These regulators will specifically say they are "Nitrox Compatible to 40%" such as the IDI Searia regulators.
Most regulators that say not to use with nitrox will void the warranty if you do because of the faster breaking down of standard O-Rings.
My opinion on this is(and im sure a few will disagree):
1. Dive with it as is and don't miss your yearly service because you will want to have the o-rings changed at least once a year.
2. you can't handle 1&2 get it O2 cleaned and designate it as your nitrox regulator.
[This message has been edited by Rebecca (edited 09-22-2001).]