Thanks for these points, bcheung! Here are my thoughts on each point: 1) The sand-based system is based on Dr. McMurtry's aquaponics research at NC State Unive

Thanks for these points, bcheung! Here are my thoughts on each point: 1) The sand-based system is based on Dr. McMurtry's aquaponics research at NC State University. Here are a list of publications about it: http://iavs.info/publications/ http://iavs.info/publications/ In general, coarse sand is a great substrate for plants. Both research and my own experience show no problems with aeration or anaerobic zones forming when set up correctly. 2) The timers are really no more complex than the pumps, so I really don't see them as adding that much complexity. 3) The way the water drains through the sand means it keeps dripping and agitating the surface for several hours after the pump stops pumping water to the vegetable beds. Of course, if you plan on maxing out the stocking density, you should add bubblers. 4) Because the water starts trickling through the sand seconds after the pump starts, you only have ~10-15% difference in water height. 5) If you want to eat the fish, might as well try to eliminate anything that might get into the fish through the plastic. It doesn't add that much cost. 6) That's a good idea, but adds the requirement of finding pure ammonia available for sale. 7 and 8) I think most people will just add filtered tap water and go with whatever pH that is.