Part 2, (Sorry about the dual posts)My experience in NW Ohio has been that winter aeration with ice cover is needed very little.I monitor my DO level with a YSI DO meter all winter long, Last year for example the ice was clear most of the time and I think this is the key. I had 14 inches of ice most of the winter and never had less than 103% of saturation and a lot of 110% or 12-14 PPM DO 38-42F and would be content with 5-7 ppm .However I will open up my winter diffuser which is a Koender Airstone with 1 cfm of air for the 2-3 days that it takes to punch a hole in the ice if I have a lot of snow cover. I always recommend a placement of this stone in 3 ft of water.One of my personal ponds is only 2 years old and was filled with well water 1.1 acre (pic at
www.cleanponds.com)my smaller pond is 4/10 acre and has 38 acres of ag watershed and is 40 plus years old.(pond on the the right in pic)This pond has a Koender windmill and the standard stone in it for winter aeration and had the same DO levels all winter. The airstone in this pond was left at the 8 ft level last year but probably only turns 300-400 GPM at that level.It did not keep open water much and had water temps in the bottom (8 ft) of about 37-38 F, so not much temp decrease due to over circulation.All ponds seem to winter differently. If DO levels are checked you can access the need to aerate or not.Letting some light in still seems to be the safest way to boost DO levels for those of us in the North.I have more concern about a aeration system that can turn the entire water column over 1-2 times per day than windmill that circulate far less than that.If you monitor your DO levels in the ponds with the airstones either electric or wind powered and they are not acceptable considering doing some research on diffuser selection. Ted
