How To Build A Winter Pond Covers

Winter pond shot 2

Many of us in the pond world have been trying to master winter for some time now to keep our pond and fish safe. Over the years of having Koi ponds I have been working hard to find a cover that will work well to protect the ponds and hold up under the heavy snow load over winter.

In this page we’ll walk you through building a pond cover at a low cost to help keep your Koi alive and not impact the utility bill in the winter.

Winter is coming what do I need to do to the pond so I don’t freeze the pipes, waterfalls and the pond? As a first time pond owner this can be a concerning time of year and the last thing you want to do is make a mistake that’s going to cost you money for repairs next season or the loss of fish. Looking around on line for ways that others have covered their ponds for the winter I have seen everything from heaters for the whole pond, floating heaters to keep hole in the ice, full greenhouse covers and even large heavy plexiglass panels that lock into place over the whole pond.

So over the years I’ve tried not covering it and I would end up with a dead fish or two.  Then I built large heavy “A” frame structures that go from side to side on the pond.  This worked but it would take two people to put them in place and storing them was a pain at 10′ long and 4′ wide they didn’t store well.

The greenhouse dome came next but I didn’t like the idea of driving rebar spikes into the ground and possibly hitting a water or power line in the ground.  Modifying the dome I used rope to connect the ends of the poles. Every thing was great until the very heavy wet Colorado wet snow hit and the domes collapsed into the ponds.

Needless to say that was not fun putting on my fishing waders and going into the ice cold ponds to get the domes back up and out of the pond. I knew this was not something that was going to happen again, so with that burned into my head the new cover concepts started flowing out onto paper.


In 2016 I finally designed a pond cover that would do everything needed to make it through a heavy winter in Colorado.


The Gridlock Pond Cover:

  • Can be used on just about any pond
  • Holds up under heavy snow loads
  • Insulates the pond to prevent freezing
  • Reusable
  • Can be installed by one person
  • Collapsible to store easier
  • No plug in heaters needed (Not reliable when the power goes out or if they short and electrocute the pond)
  • No stakes in the ground punching holes in your water/power lines
  • You can build it on your own


Now with all this being said a few things factor into how effective a pond cover is and whether or not the pumps can stay running through the winter.  The depth of the pond in your area will determine if it will freeze solid. In Colorado it’s recommended the pond be at least 2.5′ deep.

The pumps running all winter is the hard question and disputed back and forth.  The filters and pumps I have are well insulated and move enough water that it’s not an issue but you should always shut off your bottom drains.  Deep water in the winter is going to be the warmest in the pond and should something impede the skimmer your pond may drain and with the cover on you may not notice in time!

This interlocking grid design as you can see in this photo was able to keep me (at 230 lb) from falling into the pond. No this may not work on all ponds due to the size of the pond but it has been tested on my large pond that had the cover span out to 16′ wide. The length of the pond is not an issue as you can go as long as needed.

Pond cover 2The cover was created to hold the snow off the water and have an air chamber between the water and snow for insulation. At the coldest point of winter the pond had a very thin and brittle layer of ice that lasted only a day.  As the sun hits the cover during the day it heats up the trapped air layer and the ice vanishes.

Everything needed to build this cover can be picked up at your local hardware store.  (Your parts quantity will depend on the size of the cover)


Tools & Materials 

  • Drill
  • Tape Measure
  • Pen or Pencil
  • Pipe Cuter or Saw
  • #8 X 1.25″ 3.18 Construction Screws
  • 2X4’s (length will be determined by width of the pond.)
  • 1″ PVC Conduit Clamps
  • 3/4″ Schedule 40 Gray PVC Electrical Conduit
  • Clear 6 mil Plastic Sheeting (I use 20′ X 100′)
  • Bricks, Rocks, or Sand Bags (To be placed around the edge to hold down Plastic)


Step 1 – Figuring out Supply Quantities

2X4 Total:

2X4In order to find how many 2X4’s will be needed take the length of the pond (L Feet) times 12″ divided by 18″ (inches between boards).

My pond is 21′ at the longest point so (21′ X 12′ ÷ 18″ = 14), this should be your total number needed to cover the complete pond.  In order to calculate the length of the board needed, it should go past the edge of the pond by at least 12″ for good support.  This means that all the boards don’t have to be the same size you don’t need to use a 16ft board if you only need to cover a 8′ section of water you would use a 10′ board.

1″ PVC Conduit Clamps:

1" PVC Conduit ClampThe clamps will be used on every board spaced every 12” to hold the pipes in place and lock the grid together. That being said if you have a 12′ long board and need a foot hangover on each side you’ll need 10 clamps on that board. If the pond is the same width from end to end then this is an easy one to figure out. You have 14 2X4’s and you need 10 clamps per board at a total of 140 clamps.

Looking at the photo of the pond cover you will see that it’s not the same width all the way down the pond. On the wider section of the pond the boards extend further so more clamps were needed every 12” to hold more pipes.

#8 X 1.25″ Construction Screws:

The screws are only needed to attach the clamps onto the 2X4’s and you will need two screws per clamp. Knowing already that it’s going to take 140 clamps, it’s going to take 280 screws.



Clear 6 mil Plastic Sheeting:

20' X 100' 6 ML Tyco Polyethylene Clear Plastic SheetingPond width and length will determine the size of plastic needed. For example if the pond is 10’X20′ the plastic should be at least 12’X22′. I would recommend going bigger than smaller because it’s nice to have a little more to work with when you’re weighting down the edge with rocks or bricks later.

When buying a roll of plastic, I have found that it’s more cost effective to just pickup a roll that will cover the pond two times, that way you know you have enough. The cost will go down per foot the more you purchase and when it’s time to replace it you have it ready to go.

3/4″ Schedule 40 Gray PVC Electrical Conduit:

3/4" Schedule 40 Gray PVC Electrical ConduitThe reason to go with the gray schedule 40 conduit is that the thicker wall gives more support and it features heat and corrosion resistance for longevity. The conduit comes in 10′ lengths so if your pond is 10’X20′ your will need two sticks to go from end to end. Then to figure out the total number needed, add up the number of conduit clamps you calculated on one 2X4. That number dictates the number of rows you have to make, now take that number times two for the total pieces needed.



Step 2 – Bringing it all Together

You may notice that all the 2X4’s I used are just regular pine boards not PT (pressure treated) and that I haven’t stained them or painted them. Painting or staining them is recommended to prolong the life of the boards and block the absorption of water when in use over the winter. This can be done before or after you build the cover. (Don’t paint or stain over the water as this may contaminate the water)

Finding a large flat surface like a driveway or garage helps to lay out the 2X4’s and get everything assembled. Lay the boards all stacked next to each other on their sides. If the boards are all the same length, then make sure the ends are all even. If they are different lengths say you have three that are 12′ and eight that are only 10′ then center the 10 footers on the 12 footers. This will give you a foot hanging out of each end. (See diagram)

You are now going to find the center of the 12′ board and mark it as the center starting point. The line will then run across all the boards to show you the center starting point for each of them. This will be where the center pipe will sit. Now off that centerline continue making lines out to each side every 12” along all the boards as shown in the diagram.

With all the lines in place you will now start mounting the 1″ PVC Conduit Clamps onto the board lining them up on the lines across the boards uniformly to make a guide that will later hold the pipes in place. Again if the boards are not all the same length you will have some boards that need to have another row or two added to them for another pipe to support the plastic further over the pond.

It’s time to install it on the pond so bring everything out to the side of the pond and starting in the center of the pond put your first 2X4 runner in place. With the center marked now place the rest of the 2X4 runners out to each side every 18” using the longer boards where needed. When done placing them over the pond you should have all the clamps lined up and you are ready to run the PVC pipe through.

Connect PVC pipes together to make them the same length as the pond and start feeding them through the clips forming your grid cover. This can be don’t with one person as I said in the start but it will go faster with two people as one feeds the pipe through while the other can lift or lower the board to make it easier to feed the pipes through. You will find that not all pipe runs need to be as long as others so as you get them in place you can cut away the excess length or precut them if you have a saw and want to prevent plastic dust from going into the pond. The excess pipe may be long enough to be used other places such as side to side over a water fall being plastic it can go in the water and help keep the plastic cover from drooping in the water.

Note:  Make sure that the boards and pipes don’t pin down the pond skimmer lid, if need be place a brick under the 2×4’s to give you more room. If you run the pond during the winter make sure to check the water level and clean out the skimmer from anything that may have made it in after you covered the pond.

Great, your just about done we just need to unfold the plastic sheet over the grid cover and place some type of weight around the edge. Place the weight about every three feet to prevent the wind from grabbing the plastic and pulling it off.

Winter Pond Cover



  1. Excellent solution to an irritating problem.

    You seem to have reached an economical and practical answer to your heavy wet snows.

    The description you provide for this system is very detailed and complete.

    How long have you been raising Koi fish?

    How were you first introduced to Koi?

    I look forward to reading your answers.


    1. Thanks Paul,

      I’ve been into wildlife most of my life, from the air to the deepest parts of the ocean, but I started getting into Koi about 18 years ago.  It all started with a mother’s day gift for my mom, when I installed a small 200-gallon preformed pond in her backyard landscape.  Then when I purchased my own house, I really jumped in and built my first 3,000-gallon pond.  Now we have about 7,000-gallons total landscaped into our outdoor living space and about 25 or so adult Koi that I work with to bread as a hobby. I’d really love to install a bigger pond but that would mean removing one of the two ponds we have now and then digging it out deeper and wider, so I don’t see that happening any time soon. Maybe in the next house.

  2. Good solution to the problem. I am looking to make something similar in NJ. I have found a site that sells heavy duty clear plastic tarps which I am planning to use as they will let in light to give my Koi a day/night cycle. Not sure they need this but the cost is about the same anyway.

    I am also considering an electric inline water heater which are considered almost essential in Europe but do not seem to be very common in the US.

    1. That sounds great and thanks for your post.
      The clear plastic is a great way to go, with out the the natural UV getting through it has been show that the color in the koi with dissipate or even be lost as a direct result of being kept in the dark for for long periods of time.

      As for the pond heaters, in claimants we temps drop below freezing for many days in a row it’s not a bad idea. I always recommend checking in on your pond every week through the winter. Making sure your water is not freezing up to much, the water levels are good and to see that non of your koi have drifted into the skimmer and can’t get out do to being cold and week.

  3. What a great solution! We are going to consider trying this. My wife and i wondered if laying polycarbonate panels over the framework instead of the plastic sheet would work. Do you have any thoughts on that?

    1. That may work but whatever you use it needs to be able to light to come through. The other side is that you would need to figure out how you are going to seal the edges. With the 6mil you can pin it down

  4. I have some questions. I am considering building this but with a slope of about 4 inches over a 12 foot span. Any suggestions?

    1. I apologize for the late reply. You could use some bricks under the 2×4 ends and the pipe will bend some to allow for uneven ground.

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