Can you tell me if you have done some personal testing with the ecosystem?? I started off with this concept, and after two yrs of a mixed SPS/LPS, i have begin to remove the MM and replace with other substrates. I have about 2/3 of MM, and 1/3 of CC. I plan to remove the MM completely (only due to cost). I dose powder aragamight every 2-3 days. I plan to remove another 1/3 of the MM and replace it with grey coast sand. I should mention i dont use a skimmer. I run a 70gal macroalgae refug. Im just trying to understand what is really needed for the success of a reef tank. What is the best substrate to use?? Does different forms (CC vs MM vs grey coast...) really play a role in things like Iron and Calcium??