How often are you supposed to change water?? I was told that after the first 2 weeks or so u change about 25% of the tank then after that u shouldnt have to do it again unless u have a problem.
I have a post on the reef page about the same thing. Gotten several responses, you might want to look at it, may help answer your question. My reef tank is almost 3 months and I have not done any water changes yet, just top offs of distilled water. good luck!
You need a regular routine for water changes. You should never stop doing water changes. You don't need to do a lot, just stick to a regular schedule like 5% a week or maybe 15%-20% a month. Whatever works for you. There are a number of problems you can get into by not doing regular water changes. You might get away with it for a while but eventually it will catch up with you.