Hi team,
In NE Ohio with a 1 acre pond. Current surface temp after a cold week here is 52 degrees. Aeration has been off for a couple of weeks. I’m wondering what the temp would be at the bottom in 8 feet of water? Appreciably warmer?
Trying to figure our where the tilapia are and when to expect the die-off.
Thanks, Tony
Tony for your specific pond situation in NE OH my water testing experience suggests that the bottom temperature in 8ft of water will be 52F-54F. Normally I don't see tilapia dying until Nov when water at night drops below 50F. Most northern ponds are now in fall turnover and water temps are mostly uniform (well mixed). Cold nights cool the water, makes it heavier and it sinks and 'pushes' into the warmer water layers below which causes mixing. The sinking more dense cold water and wind action mixes and blends the less dense water.
In most common ponds, rarely is there significantly warmer water on the bottom because warmer water is less dense and wants to move up or 'float'. Colder denser water easily sinks into warmer water cooling it. There are some late fall - winter conditions where idle bottom water will be 1F-2F warmer than overlying water due to summer warmed bottom sediments giving up their warmth. This bottom sediment heating of summer is gradually lost as winter progresses. Warmest water in fall will be at the sun warmed surface layer. Wind action will determine how thick the warmer surface layer will be. On a nice warm sunny day with 70's this weekend,, go out an measure the temp at surface, middle and bottom to verify your fall pond conditions. Cold nights and wind easily dissipate the weak temperature difference of heated water.
Shallow ponds of 6-8ft deep will cool and warm quicker than ponds of 15ft-20ft deep. Also playing a big role in this is pond size and wind action. Shallow ponds freeze quicker and melt quicker than deep ponds due to the ability of water to naturally mix with convection and wind - wave action.
Tony,
You may not need to know the actual temperature in your deepest water.
Do you have a dock or some other means of getting a temperature from deeper water? If so, you can keep a record of your surface temp and your 4' temp (for example).
If you can observe the tilapia conditions this year, then you may have a decent predictor for future years. (Which will only become more accurate with the additional data from subsequent years.)
My water temp is the same and I have some dead Tilapia and some are still alive.