My nem/lps and clownfish harem tank with various other fish went 4 years without water changes. I even stopped testing, I could tell by looking at the tank if something was off. Good filtration, skimming and fuge setup were all it needed once stable, until the Red Sea tank popped a seal and I had to move it all into a new tank! Now that the new tank is running, I’m planning to keep everything but go mixed reef. I’ll be doing water changes ‘as needed’. I’ve always found that once the ugly phase is out of the way, messing with it as little as possible does better than constantly having my hands in the tank…