Probably a good question for Esshup to weigh in on. We've pretty much been in a drought since about early August with very little rainfall. Almost every wet hole or swamp is nearly dry and most farm ponds are down a couple foot.
If we get a hard extended freeze assume there will be a higher probability of winter fish kills in farm ponds?
Yes. You can have a winter kill within a span of 2 weeks of no sunlight getting to the pond water. That is where winter aeration comes into play. 2" of cloudy ice and 2" of snow will cut off the majority if not all sunlight getting into the pond. That stops any plants that are still alive and all the phytoplankton from producing O2 and they start consuming O2 to live. Also the bacteria that is in the sediment in the pond bottom consumes O2 along with the fish. That is called the biochemical O2 demand.
Think of the total volume of the water in the pond as a bank account. Start out with less water in the pond, you start out with less $$ in the bank so to speak, so if you have the same bills to pay (or fish in the pond) the money (or O2) runs out faster. The ONLY savings grace is that cold water can hold more O2 per gallon than warm water.
For my personal pond, it has dropped more than 50% in volume. It's gone from slightly more than an acre in size to slightly less than 1/2 acre in size. When it did that last year, I removed roughly 60# of fish from the pond to help lower the O2 demand. The fish didn't pull off a spawn this year, and with no cover in the pond the bigger fish went to town eating the smaller fish so there is less fish biomass in the pond this year vs. last year. Even though I put 50# of trout in the pond this Fall, I think I am still OK because I run an aeration system in the pond.
Water has an affinity for O2 just like brake fluid has an affinity for water. Water will gain O2 when it comes into contact with the air. Plus water, when in contact with the air will outgas, and the gases that are toxic to fish that build up in the water (like Hydrogen Sulfide - H2S) will dissipate. Those are the 2 reasons why winter aeration (if set up correctly) will greatly minimize winter fish kills.
A winter aeration system doesn't have to be elaborate and one can be built and installed for a lot less money than a summer system. It all depends on how far away electric power is available. A 1/3 hp compressor, that furnishes 2 CFM air at 4 psi will be plenty, but more air is better of course. Then you just need air hose to get to the pond, weighted air hose for in the pond, any kind of diffuser (the coarser the bubbles the better) and a way to keep the diffuser in place in the pond at 1/4 to 1/3 the total pond depth, approximately 20 to 30 feet from shore. If the diffuser is placed in deeper water, it will cool too much of the water, and that will stress the fish, especially Redear Sunfish, Bluegills and Bass, and most likely to bacterial infections due to the stress.
Ideally you want to have 10% of the pond surface open to the air, but I've seen it work with as little as 2%. A single coarse bubble diffuser set in 4' of water with 4 cfm opens up a circle of open water up to 50+' in diameter, depending on ambient temp.
Most of the guys here are DYI types, so I'll list some of the basics.
Compressor - A rocking piston or rotary vane type will last longer and work better than a diaphragm type. I like the Gast 0523 type compressors. Long life, super easy to rebuild (although the rocking pistons are relatively easy too) more air volume per hp than the rocking piston type for shallow water applications (less than 20' depth)
www.grainger.com/product/4F740?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gclid=Cj0KCQiAtICdBhCLARIsALUBFcGjDfZ3nbaqlWX3HTYh9vCCfJp2L9uiaSK_lULaJ19XHrtPZtdBSJ0aAnn2EALw_wcB&gclsrc=aw.dsYou will have to either figure out a way to jury rig a better air filter than the muffler that is on there now or buy one from someone. I will weld up some metal so I can use a conical shaped one that is for a Tecumseh gas motor, or I can source one from my suppliers.
shop.hoosierpondpros.com/Air-filter-for-rotary-vane-compressor-Rtryvnefilt.htm This can be adapted to any compressor with pipe fittings.
If the compressor can't be placed by the pond, I will trench in low pressure black poly pipe (1" dia) from where the compressor is to the edge of the pond (better to do this when the ground isn't froze). Then adapt it to the 0.58" ID self sinking hose for in the pond. This hose has 1/2" thick walls and weighs 1/2 pound per linear foot. Don't screw around with non-self weighted airline - it isn't worth the hassle. Been there, done that and won't do that again.
shop.hoosierpondpros.com/Vertex-BottomLine-Tubing-058-ID-50-roll-50BLT58.htmFor a winter diffuser (these won't work properly for summer use) I like using these from Zoro - they are inexpensive and open a larger hole than the fine bubble diffusers that we use for summer use.
www.zoro.com/atlantic-diffusers-diffuser-coarse-bubble-disc-5-in-dia-ab-70003/i/G4010237/Of course you will need something to weigh it down (rope and a brick will work), assorted fittings to convert pipe thread to barbed fittings, and a box that allows ample air flow to the compressor but still protects it from the rain and snow. For the winter I will use one of those square dog boxes. If you don't have ample air flow the compressor can build up heat and cook itself.
This is used from when ice forms on the pond to when ice goes off. It is NOT sufficient to aerate your pond for summer use - that is much more detailed. For that we have to get into figuring the total water volume in your pond, the bottom contour to figure out the depth of the pond, etc., etc.
I hope this helps a bit.
