Question About Pond Aeration During Winter:
"Somone told me that during winter I should not place my air line all the way to the bottom of my pond. If I did this it would super cool the water and fish may die. They said half way down was the correct location.. is this true?"
Well there is an ton of bad info on the net these days about pond aeration during the winter months. Most it the info out there is just regurgitated info they heard from someone else that was never questioned or tested.
The super cooling effect can happen in very large ponds, but your typical backyard pond with koi is not suspect to super cooling.
What usually happens in a typical setup for aerating a pond for winter is that you place the aerator in the center of the pond at a depth that creates a plume.. with enough force to not easily freeze over. This plume causes the water to rise to the top of the pond and then flows to the sides. It hits the sides and then down to the bottom it goes. So really in these small water features the whole body of water is getting circulated no matter where the air line/ bubbler is placed. Which you want the whole pond aerated with no dead zones.
If you do have dead zones you may want to add mulitple spots with aeration depending on the design.
The key to winter pond aeration is to get it going as early as you can. In fact its best to have it going all year. But, if that is not possible once the water starts to cool start the air.
If you were to wait until the water starts to freeze then... you can "super cool" a pond in a sense by mixing the warmer and colder water on the top and shocking your fish that are on the bottom of the water feature.
So.. to sum it up.. your water if properly done will most likely be around 32 degrees top to bottom and if possible place your pond aeration in the ceter on the bottom. This will allow the aerator to keep working when ice forms and water levels drop.