I have asked Sue with Vertex to post a simplified flow chart that gives an example of various airstations at various depths with the constant being 1 cfm per disc. This chart is available at www.cleanponds.com on the home page. Link onto the 2011 catalog and scroll to page 18. Hopefully Sue can post this and save you the time.To know your lifting rate you need to work with the diffuser manufacturer or Airstation manufacturer that has taken those membranes and put them in a set configuation and has tested them. Testing can be done at various independent sites and some manufactures are now doing inhouse and or extrapolated testing.Results reported in gallons per minute are common, Once you have calculated your total gallons in your pond simply do the math. For example if we have a 1 acre pond 9 ft deep on the ave lets say we have 2.9 million gallon or 9 acre ft. If we know a station tests at 3000 gpm at 2 cfm in 9 ft of water that is 4.3 million per 24 hour , divide your 2.9 into 4.3 and you have 1.49 turns per 24hr day.Placement of station(s) will come into play with the shape of the pond.Not all difffusers are tested since they may be primarily designed for wastewater inwhich they are spaced close together on large tubes and are creating a super saturated condition.This an entirely different concept. Pond diffusers utilize the atmospheric oxygen to add oxygen to the water.Waste water diffusers are often sold for pond aeration but can be difficult to know how they are performing.Some diffusers are made specifically for bottom diffused aeration inwhich they have been tested and achieve high lifting rates with low cfm's. This will be a good starting point to get this thread started.More to come !!