First off, covering your pond during winter is not a requirement. I’ve had several seasons where I’ve left the pond uncovered without dilemma. However, if you are near trees or have leaves flying around, you won’t regret a cover as come spring there will be little rotted debris for you to have to fish out of the pond. If you enjoy mucking and vacuuming a pond, then by all means you are free to wing it without a cover.

Building a cover for your goldfish or koi pond for overwintering is pretty straightforward and can be done relatively inexpensively with minimal DIY skills. You can choose to cover your pond with many materials, but most pond folks use either a pvc bird netting or an opaque plastic tarp. There are pluses and minuses to each material: netting allows you easily see the pond still and is sometimes barely noticeable. It will serve to keep leaves and other debris out of the pond. Tarp will be far more obvious (and some think ugly) in the yard, but will keep out the typical falling debris and also some of the harsher weather. A tarp can also keep the temperature of the pond up to 10 degrees warmer sometimes. Do not use a tarp that isn’t clear or opaque as koi depend on sunlight and will not do well sitting in complete darkness for so many months.

Let me start by saying that simply laying a tarp or netting flat over the pond and securing it with a few stones is a mistake. I do not recommend this design because as debris, rain or snow falls onto the cover, it begins to weigh it down and it will start to sag into the pond. This is the lazy man’s approach and you will cause you nothing more than headaches. You’d be better off just leaving the pond bare. Be warned that any proper pond cover should have some kind of frame to support it.

 

Let’s talk framing materials: My preference is to use PVC or conduit pipe to build a frame over wood. For one, it is fully weather proof and lightweight. Second, it can easily be put together and taken apart each season and stored away. You simply buy a few appropriate elbow fittings and put everything together. If you’ve got wood laying about the yard, by all means use it. I would recommend using screws instead of nails as it will be easier to dismantle it once spring comes.

 

Another consideration for you to ponder is the height of your structure. Some folks want more of a tent instead of a cover so that they can walk inside. Therefore, you’ll need to build a structure that can allow for the height of a human. In this case your structure will need more support in order to account for its height, and it will cost more to construct. Others simply want a light-weight cover that is just a foot or so higher than the pond itself. I’m just trying to keep out the falling junk and some of the crazier weather that may come, so a low cover suits me just fine. You need to decide for yourself what you prefer.

 

There are 3 basic designs:

 

A-frame: As the name implies, an A-frame has a peaked roof and looks like a traditional greenhouse.

 

Hoop/Dome: This particular design is perfect for PVC, since the pipe is flexible and bends easily. This site gives clear instructions on how to build one that is tall for only $50 bucks.

 

Going Flat: If you want to keep things simple and don’t want to build a frame, there is one way to go with a flat structure that will give plenty of support, and that is to use corrugated plastic roof panels at your local home improvement store. This is the most expensive option as they run about $20/US per panel depending on their size, and you do need a pretty level surface to lay it on to begin with. But basically you just lay your panels down and then secure them so they don’t fly away in a good wind. You can drill some holes in each panel to connect them together with some screws and also stake them into the ground. If you live in an area with heavy snows and have a wide span between your pond sides, you can simply build a PVC pipe support and sit it in the middle of your pond so that the panels don’t give way from the weight. This design is best suited for ponds that are above ground and rectangular or square shaped.

Get more tips on winterizing here.