The first step is to think about it. Why do a water change?
The industry generally recommends a periodic water change of a certain %.
We do about 20% every two months, sometimes monthly.
Why? Good question.
Because most everyone else does. It can’t hurt.
We don’t dose anything so the new salt water in includes elements that are consumed by the day-to-day biochemistry of living corals, fish and inverts.
Who knows what is settling into the tank from the outside air. The water changes would mitigate to some extent.
If the water has degraded to the point of being harmful, will a 10 or 20% dilution of the pollutants be helpful? Doubtful.