Excellant reply's everyone, it's great to hear all your different views
I would say IMO that water changes are essential for all reefers to perform. Different strokes for different folks however- for example if I had a larger stable tank such as Steve mentioned then maybe I would be inclined to still do a waterchange but just of a lesser volume. Also like Beverly mentioned I would do more frequent waterchanges if I had a smaller tank that was not as stable.
With that said I still believe that water changes are indeed a must for any tank. I premix my new water for about 3 days before changing 15% of my total volume, allowing PH and Alkilinty to reach tank levels, and also to provide good aeration.
cheers, Rich
