welcome aboard!

Sounds like you have the right idea - do you have the c filter inside the tent, and then the fan blowing out through the ducting? That way the smell never makes it outside the tent - I recently installed one and it really worked - no smell outside the tent at all. Do a test - turn it on, go outside by the vent and take a big whiff - anything?

good luck - just did my first harvest yesterday with your same basic setup (600w hps) and very happy with it!