The circulation pattern is sometimes affected by wind and waves.
Absolutly, but it's several dead calm nights in the heat of the summer when the algea is blooming hard that I worry about, it's that 15 minutes of no DO that worries me. In a scenario where there is no wind and waves present a bottom diffuser is much more limited to the immediate area surrounding the bubble column that it is aerating. In smaller 2-3 acre ponds they are very capable of turning over most of the water in the pond, in a much larger pond like ours a single diffuser can only create a realtivley small refuge area. The DO crashes we have expierenced have almost always involved dead calm conditions for several days in a row before the crash occured. The one crash that did't involve calm conditions was copper sulfate induced. The last DO crash we had was localized to just the shallow weedy area of the pond after a stong cold front came through and a sudden algea die off occured.
Shorty mentioned "Notice the shaft is at a 45 degree angle creating current on the bottom." I ask, how deep is the bottom?
In that picture, 7-8ft, minimum operating depth of this type of aerator is 4ft, otherwise it digs holes on the bottom and suspends sediment in the water. There is a boat prop on the end of the shaft that spins at 1750 RPM's per minute, a 2-1/2" hole at the top of the tubing allows air to be sucked in and spun out through the center of the prop. It does create a deep circular current along the deep weed lines around our 9.9 acre pond. In the picure I posted those aerators are on the north side facing west, 150 yards straight south of the aerators the deep water weeds are consistantly being laid over and are pointing in the opposite direction to the east in 8-9 ft of water. Now if I could turn over most of the water column in our 9.9 acre pond with one or two bottom diffusers I would, at the moment horizontal aeration seems to be the best answer for us. So, the size of one's pond does matter when looking at aeration options. I did check their website and this type of aerator is suited for ponds up to 15ft deep. Keep in mind that the company that makes these is is primarily in the the business of manufacturing aerators for waste treatment plants, their pond aerators are just a scaled down version of the commercial units they make for WTP's and are not their primary line of business.
