Pond Boss Forums AERATION Systems questions Turnover rate-Ted?- anyone?

Are there any guidelines, "rule of thumb" as to how much turnover there is in gallons per day at a given depth?
I realize it varies with cfm, size and amount of bubbles, depth, etc.

Example: 1.5 cfm at 8 ft depth in 300,000 gal. water with max depth 12 ft, av. 5 ft. Using 9 inch membrane diffuser with 6000 slits and placed in a 5 gal. bucket and sunk.
Looking for non specific answer ie. 1/2 per day, once per day, 2 or 3 times per day?

Great question, There are very specific water turnover rates established with some diffusers and no rates with others. The main difference being diffusers designed for pond and lake aeration only and others that are designed as wastewater diffusers (require lots of cfm) and have entered the pond and lake aeration market and sold as a "diffuser is a diffuser"(View the Ecologix web page some time) One of the keys is to establish how many "turns" per day you want or need. This number can vary from a lake of many acres with as little as .75 turns per day to a intense setting like Cecil has and may have a 2-4 turn per day. This is where a rule of thumb can come into play. I never size less than "one" turn per day unless I have a situation like cold water fish that need to stay at 55-60 F in a warm climate such as summer in Kentucky . (Night time aeration comes in to play in that situation) Also to be considered are the water source the fish load the expectation of the pond manager, plant load, grass carp (yes or no)age of pond, (high organic load,muck)care in the past to name a few.Considering these things you may want /need 2 turns per day. I have one pond that is maintained by a well that has very hard water and high levels of iron and sulfur,I can turn that 4 million gallon of water over 4 times per day if needed to lower those water traits. To be more specific to your question, independent testing of diffusers is rare. I sell only independently tested diffusers as its the only way to "properly" satisfy your turnover goal. An example of a tested result would be 1 cfm supplied to a CoActive Airstation in 12 ft of water will turn (lift) 2778 gallon per minute or 4 million gallon per day. The 9 inch membrane you are referring to may have 6000 slits but they could be .5mm slits or 1 mm slits or I formation or Y formation and they all effect liftng capacity. I always hesitate to guess a lifting rate on a diffuser when I have the exact data on my diffusers at hand.I have some independent test results of some competitors diffusers on my site you may want to view.The Vertex results start at 4 feet and go from there.A little off the trail but I have also added a link for a "free" aerial view of your pond or lake or tank for diffuser placement to my site also.Most ponds built from 2002 can be found.Lets assume you have a goal of 5-7 ppm (mg/L of DO) which is acceptable for warm water fish and you want to maintain 80-90% saturation which is excellent for most aquatic organisms. Muck reduction will take place at this level.This would be your goal. To be factored in are as many of the above considerations as possible (age,depth nutrient load etc)and now you ready to establish a turnover rate for your pond or lake.This was the long way around your question and I hope I answered it to a degree, Ted

Outstanding answer,Ted! Ladies and gentlemen, he knows his stuff.