A simple structure over the top of your pond in the winter months will help your Koi ease through the winter and provide a much earlier spring start. For years, I relocated my Koi into a 300-gallon stock tank in the basement of my house. Had the Koi not reached a size prohibiting the stock tank, and my better half not appreciating the Koi in their indoor home, I would have continued and created a larger indoor pond. With that not being a choice, I constructed the dome to cover my pond.
The framework of my pond cover consists of 2 inch electrical conduit, 20 mil clear greenhouse plastic, 24 inch rebar stakes, zip ties, 50-lb sand bags and a lot of duct tape. My wife still teases me about the duct tape but it plays an important role in the stability of the structure. The cover is relatively simple to construct and, depending on your pond size, can be done in one day. I chose to shut down two of the ponds and covered just the main pond.
Framework is assembled and placed over the pond in a hoop-house fashion. The main ribs are every 4 feet and extend an extra 5 feet beyond the length of the pond to allow entry for maintenance and checking on the Koi. The ribs are slid onto the rebar stakes that are driven into the ground about 12 inches.
Next, the center and sides supports are added. If you are located in a zone with light snowfalls, all that is needed is the center brace at the top once all of the ribs are in place. Being in Northern Wisconsin, I am not so lucky. I have added extra support on the sides as well. The zip ties are used to secure the side and center supports to the ribs.
Once all is in place, the rib and center support crosses are secured with a generous amount of duct tape. This keeps everything from shifting and helps support the weight of heavy snowfalls. Applying the greenhouse film is as simple as unrolling and sliding over the top, allowing 2 feet of overlap on all sides. Sand bags are used every 3 feet to secure the plastic to the framework. This has worked for 3 years now without mishap. A zipper for plastic construction sheeting is applied at both ends of the pond to allow entry.
I have chosen to heat the air in the dome with an infrared heater commonly used in the home. Water temperature stays around 45 degrees. The main pond has a depth of 8 feet, so the water temperature does not fluctuate much. If you do not heat the air, a floating pond de-icer can be used.
I have not turned on the heater yet and my de-icer as well as the sun has prevented any ice so far. Feeding has slowed to just algae grazing on the sides of the pond. I have a 10,000 gallon per hour pump located near the surface for water movement as well as an aerator in the shallow end of the pond.
Preparation for the pond prior to the cover consisted of a 50% water change, removal of all debris, the addition of pond salt, Stress Coat and Microbe-lift to consume any waste or missed debris. Water parameters are still checked daily and, as always, a close eye is kept on the actions of my Koi. They will fade somewhat in color over the winter, but should still appear vibrant and healthy.
My next post will cover winter health and common ailments.