According to the chemistry on their website, it appears that it basically puts denitrifying bacteria into your tank. The extra oxygen is required for these bacteria, and they basically reduce (pun intended, oh ho ho) the nitrAte to nitrogen gas, which I assume will escape out of your tank during gas exchange.
It also increases your pH and alkalinity to prevent pH crashing from the nitrogen cycle. (Apparently)
In my opinion, I would probably have to experiment with this first. Take a bucket of old water from a cycled tank and try it, numerous times. Personally I would just stick to water changes and/or a boatload of plants that take care of the NO3 for you.
Last edited by bahamut285; 05-06-2011 at 08:43 AM.