I hate to say it, but your "aeration" sounds like a complete mess and is doing nothing properly, except burn a LOT of electricity. A lagoon does not even need aeration if the load is small, but things happen faster with proper aeration. 6 foot depth in the main ponds is too shallow for bottom membrane diffusers, but runs of hose can help. A surface agitator or two is probably best with the shallow water.

Here are 2 links...The first is on proper lagoon design and the second is a company that sells diffusers designed specifically for waste water treatment......

http://extension.missouri.edu/p/WQ402

http://www.wastewater.com/parts