All diffusers have a % of OTR (Oxygen Transfer Rates). In an aquaculutre setting and large capacity fish farms, this is a very important number to know. For example, the 9" stone diffusers used by Aquatic Eco in an "H" pattern could support up to 5,000# of warmwater fish. That was back in 1998. They have since improved stones and membrane diffusers so the same set up may be able to support a greater amount of fish.
Aeration in the matter we use it in normal home ponds should be termed "Circulators" in that we are using the bubbles as a lifting apparatus opposed to bubble oxygen transfer efficeincy. It has been said by the late Bob Heideman with Aquatic Eco Systems that the bubble transfer is less than 5% when using compressed atmospheric air. Heck that is only 20% oxygen anyway.
This is why it is important to know what the oxygen levels are at a minimum during the am hours and what they are through out the day and best option during a full month before sizing an aeration system. This will allow us pros to look at data "we love data and graphs" and design a system that will meet the oxygen demand the pond has both for worst case scenerio and shock load. The term turnover rates is ambiguous and is very broad. We found that many pond owners did not know what the oxygen levels were so we had to make assumptions to what they may be and match a turnover rate to meet that assumed oxygen demand.
Now that test kits, meters and informed pondowners exist, we as pros need to get back to the specfics of aeration design and literally custom design a system to meet those demands and provide the OTR and SAE (Standard Aeration Efficiency) for each system. OK off my soap box.
