I change 5 gallons out of my 29 every week. It is only two months old so I will probably reduce this to once every two weeks soon. I have also noticed that the tank is happier the day after a change.

My LFS has told me several times to leave it alone and it will be fine... I am just used to it from my freshwater experiences.

Good luck in finding an answer, I will definately check back and see what everyone else has to say.