Denitrators

[...]
"...disguising the need to do water changes." ...hmm If something
causes your nitrites and nitrates to be very low than why would you NEED
to do a water change? Just for fun?


So you are saying that over time the water chemistry
will not change in the closed system like a reef tank ?

This is called setting up a "straw man". No. I am not saying this at all.


You know, there are much more different ions there
beside NO3-...

Yes, I am aware.

With partial water change you replenish
ions used up by growing animals/plants in your tank.

I add trace elements (Kent Marine Essential Elements) on a monthly basis.

You also remove organic byproducts your skimmer left behind.

Such as?