I really never do water changes except after a major cleaning or something that really disrupts a bunch crap. But I have a ton of DIY
stuff to auto top off with Kalk
, a denitrator, and both a sump and a fuge of about 20 gallonas a piece. The only thing I do on a regular basis is test and adjust my trace elements. Other than that, I have actually found water changes to disrupt my system. In reality I think it depends on both your tank setup and philosophy toward adding things to your tank, some people only add minerals through water changes, I personally prefer using a combination of trace elements and specific addiitves. But remember, always test before you add things to the tank because too much is often far worse than not enough.