Water Changes

Generally speaking, our goal is to manage in a relatively small closed system,  an environment that mimics the natural environment of the animals and plants we are keeping -- think, Great Barrier Reef (a very large, open system).  Note though that wide variations appear to all "work" successfully.

On a natural reef, there is a constant flushing of the ambient water.

General rule is 10% of system water volume per month.  Some reef keepers do a higher percentage more frequently.