I don't add anything to my tank. Water changes are the about it. Occasionally I'll get a wild hair and I'll check pH and if that's off, I'll whack it with some kalk or baking powder if it's low. I'm getting a calcium reactor soon, so I'll probably be more diligent with testing. For a while at least.

I'm the laziest reefer out there. I can honestly go months without testing things. If things look good in the tank, I'll assume that it's all systems go.