Milan
Aquarium Advice Regular
Based on the parameters you posted, what you really need is a PWC. 80ppm for nitrate is high. It should be arround 10ppm, if i'm not mistaken. Here is the link to information on how to quickly deal with elevated nitrate leves.
http://saltaquarium.about.com/cs/nitratecontrol/l/aa091901.htm
http://saltaquarium.about.com/cs/nitratecontrol/l/aa091901.htm