IMO our fish will tolerate super cooled water a lot better than water without DO. As the pond water gets cooler it may result in a smaller aerator opening due to the water is not as warm (39F) and the melting at the opening is not as 'intensive'. I would still run your aerator as previous. If you are not applying all the air of the compressor then divert some extra air to the diffuser and the opening will become larger. A weather warming is coming the end of this week and next week. Then the diffuser boil opening will increase in size. If you want to know the current temperature of the pond water take a small thermometer and place it in a container that has a handle. Tie a cord to it, fill it with cold water and toss in into the boil area. Let is sit submerged for several hours. Retrieve the container and read the thermometer. Report your findings here.
