Most people seem to address the water change issue from a nutrient point of view. Nutrients can be filtered out, there are many ways to do it with good equipment and media. There was an article in Coral magazine a while back asking the question "are water changes necessary" and it was concluded that normal water changes have a minimal impact on nitrates. I think the biggest challenge would be how to restore the depleted trace elements. The big three (calc, alk, and mag) are no problem but we all know there are a great deal of other elements that are essential, difficult/impossible to dose, and only seem to come from a fresh batch of reef salt. It sure would be nice to have a way of running an SPS tank without water changes but I think we're a long way from it right now.
|