Winter Koi Pond Cover

by Drs. Foster and Smith on December 21, 2010

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Ready For Winter

Ready For Winter

**Guest post from Heath S.**

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. 

Frame Work

Frame Work

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.

Inside The Dome

Inside The Dome

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.


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Winter Koi Pond Cover a Success! | www.DFS-Pet-Blog.com
December 27, 2012 at 10:42 am

{ 3 comments… read them below or add one }

Jennifer December 21, 2010 at 11:38 am

Thank you SO much for the article Heath! I, too, live in northern WI so the info is very much appreciated! Especially the extra attention given to reinforcing the frame so it can support the snow load. And, this year the snow has been coming very fast and heavy so, as you know, that particular detail is a necessity!

This is my first winter with koi and I agonized about whether to attempt wintering them in the pond or bringing them indoors. After learning a bit more about how koi in their native Japan go through the year in outdoor ponds and how their metabolisms are capable of slowing down in order to help them survive the cold water temps, I decided to just take the plunge and attempt to try them outdoors. Over Labor Day weekend, I added an addition to the main pond that is over 6 feet deep to accommodate the koi for the winter. I read a lot about wintering koi and got some plans from a retired university professor from the New England area who had used his method to successfully oversights his koi in a 4 foot deep pond for over a decade.

Still, I worry every time I look outside and see the pond because I’m aware that while winter temps in WI are similar to the temps in the northeastern states, in WI we get some seriously low low overnight temps in January (or in the case of this year, in December too) that will go into the minus 20s, 30s or even 40s that the northeast doesn’t usually see. It is a real test of faith wondering if the method I used will work or if I will end up with several hundred dollars worth of dead koi plant fertilizer in the spring. I definitely will be using your method next year to help alleviate some of my anxiety over my kois health! Thank you again!!! And if you have more pics of the frame and/or full structure, I’d appreciate it since I tend to be sometimes a bit mechanically challenged asi learned while doing the plumbing the pond. Thanks to you and the many ponders I’ve met out there on the Internet who have helped me navigate all the pond dilemmas I’ve encountered along the way! Happy Holidays to you and the rest of the amazing Drs Foster and Smith staff in Rhinelander!!

Heath S. December 22, 2010 at 2:14 pm

Jennier – So far we have had 2 major storms in Northern Wisconsin, one being especially windy. The dome did not fail. We have had several days of frigid temperatures and still no ice forming. I have not started the heater but have begun using a deicer just to be safe. One other tip, without the use of a heater for the air frost will build up on the inside of the plastic sheeting, this will block the heating effect of the sun from getting into the dome. To beat this you can use a small ceramic of infared heater early in the moring and this will melt the frost allowing the sun in. If a heater is not available a broom can be used to gently bounce the frost off. More pics soon!

Neil Buboltz November 26, 2012 at 2:48 pm

Hi, I also iam keeping my Koi and goldfish outdoors in my pond and my pond is only 2.5 ft deep and my friends next door have been keeping their goldfish in their pond with only 2 ft, with no cover for several years now and none have died, but this year I bought a unit from Fleet farm that does not eat your electricity bill up it releases the gas thru a vent that only heats a tube and cost no more to use than a light bulb (much cheaper) then a stock heater.All you need to do is keep snow from covering the tube. I Live by Spicer, mn and it gets cold here. Like -10 degrees thru -40 degrees below zero. But snow over most of the pond insulates it from going down more than 2 ft and the unit I have lays in the deepest part of the pond.

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