It works kind of like Hagens Cycle. It has "microorganisms" to help balance the tank. You have to use 1 teaspoon per 5 gallons of water weekly for it to work and when you do do a water change to take out 50-75% of the water, then not to change your filter carts. for 7-10 day afterward. you can look it up with all the info. on it on Tetras web site
http://www.tetra-fish.com/index2.html
I would just not use it and do water changes. I would have to use a ton of the stuff with all of the tanks I have.