Leo:
When the O2 levels were monitored last winter, and found to be good, one of the ponds had a windmill diffuser running in it. Pond #2 was chosen to leave the diffuser on because that pond was almost the identical twin of Pond #1 in regards to pond age, depth, number of species and amount of fish stocked. Both ponds are constructed the same way, and judging by the surrounding trees, they both have the same amount of organic leaf litter entering the ponds.
O2 levels were checked in the deepest portion of the pond at 1' below the ice, 3' below the ice, and so on until 6" above the bottom.
Some cliff notes:
January 2011
Pond #1 7.5" ice, 6" snow
1' - temp 33.6°, DO 6.54 mg/L
3' - temp 35.3°, DO 5.68 mg/L
Couldn't measure deeper water due to thin ice by diffuser that wasn't shut off 100%. The diffuser valve was accidently left cracked open enough to create a wet spot or very tiny open area in the ice, no more than 2'-3' in diameter during periods of sustained winds. The same diffuser in pond #2 kept the ice open in a 20' to 40' diameter area around the diffuser. I don't think the diffuser in Pond #1 contributed much if any to the O2 levels.
Pond #2 windmill aeration in shallow area, same ice/snow as Pond #1
1' - temp 33.7°, DO 7.01 mg/L
3' - temp 35.8°, DO 6.69 mg/l
cannot test deeper water
Pond #3 No aeration
1' - temp 33.9°, DO 11.54 mg/l
3' - temp 39.2°, DO 9.01 mg/l
4' - temp 39.8°, DO 7.58 mg/l
8" ice, 6" snow max water depth 4.5'
My pond no aeration 5" ice, 4" snow
1' - temp 36.2°, DO 10.9 mg/l
3' - temp 37.2°, DO 8.95 mg/l
5' - temp 39.1°, DO 8.80 mg/l
7' - temp 39.2°, DO 8.72 mg/l
9' - temp 39.2°, DO 8.73 mg/l
11' - temp 39.2°, DO 8.71 mg/l
February 2011
Pond #1 11" ice, 4" snow
1' - temp 33.3°, DO 5.98 mg/l
3' - temp 35.2°, DO 5.55 mg/l
4' - temp 35.8°, DO 5.05 mg/l
Pond #2 10" ice, 4" snow
1' - temp 34.9°, DO 10.4 mg/l
3' - temp 37.9°, DO 10.2 mg/l
4' - temp 38.9°, DO 8.85 mg/l
Pond #3 11" ice, 4" snow
1' - temp 34.8°, DO 9.26 mg/l
3' - temp 38.6°, DO 7.71 mg/l
4' - temp 40.1°, DO 4.72 mg/l
My Pond 7" ice, 4" snow
1' - temp 34.3°, DO 10.4 mg/l
3' - temp 38.9°, DO 6.93 mg/l
5' - temp 39.2°, DO 6.91 mg/l
7' - temp 39.2°, DO 6.63 mg/l
9' - temp 39.3°, DO 6.48 mg/l
11' - temp 39.3°, DO 6.39 mg/l
This is all data that was before introduction of HSB/RBT. In my pond, I have a pretty high biomass of fish, I'd estimate at or exceeding 500#. No O2 data was acquired this year as I gave Cecil his O2 meter back. I added 50 RBT to my pond this year, sourced from the same supplier as the winterkilled fish, and stocked at the same time. No morts are observed in my pond this year, but I am running an electric compresser with the one membrane type diffuser set at the 7' to 8' deep mark.
On the winterkilled fish, there were no lesions, sores or any other visible signs that the deaths could be linked to a pathogen.
