Don't fix what isn't broken?

Huge confession and don't hate on me... I haven't done a water change in 4 months ( ok, a couple of 10 gallon ones) Testing reports optimal levels: calcium 480, dkh 10, phosphate and nitrate undectable. It's a105 gallon mixed reef. Additions are 2-part dosing with dosing pumps, kent trace elements once per week, GFO reactor, ATO. I have been doing the daily maintenance... Change the filter sock, and dump and clean skimmer neck. I test every two weeks. My wet pets are a Kole and yellow tang, six line wrasse, a pair of snowflake clowns, a spotted mandarin and two Bangaii cardinals. I am really enjoying this low maintenance reef.
So if it isn't "needing" water changes, why do one?

 

WC accomplish 2 tasks which I can think of, Nutrient removal, and Mg Cal alk and trace element replenishment. Sounds like you have them all covered.

 

There are at least two you're not accounting for. Long term, all the stuff you add could be putting in more of some element, copper or tin for instance, than you're taking out. Similarly, over the long term, some minor nutrient or trace element is getting depleted.

Water changes are an insurance policy against long term buildup and depletion. In their absence, everything will chug along fine until something gets out of whack and you'll start wondering why X isn't opening or why there are no more of Y critter and slowly it comes off the rails.

Do the water changes.

 

I've done it both ways. I've now decided on monthly- 52g WC's- that's ~20% for me.

I gotta tell ya, I agree with my fellow Texan on this one.

While things are going well, maybe at least a 10-20g every two to four weeks?

You want things to keep going well, right? If it ain't broke- do a bit of preventative maintenance to keep it going well.

 

That all makes a lot of sense.