Pond Boss Forums AERATION Should I aerate? Super Cooling?

Super cooling, as my old foggy mind recalls it, was something that was discussed early in the history of the Pond Boss Forum. I was a part of those discussions and probably contributed to creation of this aeration concept in ice covered water. The super cooling in winter has little impact in ponds that have little or no ice cover. As more discussion and knowledge on the topic has been gathered, I currently think this super cooling concept may be over rated for most warm water fish, and all cool water fish and cold water fish. The exceptions are with the southern adapted fish varieties or species such as Florida LMB, CNBG, RES, etc. and maybe some CC or blue cats.

Similar to what 'esshup' noted above, the coldest temperature that I have measured the water temperature of aerated ice covered ponds is at 36F in a pond with full depth bottom diffused aeration, 24/7 aeration, and cold winter temps for weeks with air temps below 32F and some close to 0 or below.

Cecil Baird1 and a few others have noticed redened mouth teeth areas of LMB in super cooled water. PB members concluded this characteristic was probably a stress factor and due to water temps below 39F. Others have noted increased deaths of southern sourced RES during aeration in winter. This too was probable due to cooling of aerated water in winter below the 39F temperature. Thus there is evidence that super cooling can stress fish. The degree of this super cooling stress will depend on several variables including fish species.

After discussions with Matt Rayl (Aquatic EcoSystems Ecologist) and my testing, we conclude the super cooling is probably over rated in northern waters inhabited by northern adapted species. This is because most of the northern species readily inhabit streams that develop water temperatures that are significantly lower than 39F in winter. I've measured frozen weather creek temperatures that have been as low as 34F with no observed major stressors or fish deaths. These stream dwelling northern fishes are adapted to moving water with quite low winter water temperatures. These fish survive year after year. Thus I think the super cooling concept does occur, but its impact on nortrhern adapted pond fish is minimal and less of a stressor compared to very low DO due to no pond aeration in very cold winter air temperatures. Would you rather have your fish stressed in 37F water temps with aeration or dead without aeration in 39F water in a severe very cold winter? However there is a lot of 'middle ground' with operation times and placement of diffusers for aeration during winter.

More testing an input on this topic will result in an evolution of the super cooling concept.