Pond Cover with Window

When you cover a pond, you trap Carbon Dioxide (CO2) gases inside. As you know the fish and all the other living things in the pond use Oxygen and give off CO2 even in the cold of winter. So if the CO2 cannot escape, it builds up in the air and in the water. If it builds up enough, it will stop the fish’s gills from releasing the CO2 in the blood and the fish will suffocate and die. Also, excessive CO2 is acidic, so it will push your PH lower and you can get a PH crash which will also kill your fish. So it’s really important to add a source of outside air under the cover. The more air the better, but depending on your pond size, even a few large air stones driven by decent size air pumps will work for most people.

I left the PVC arches in place for this year and just added the window framing over them. The window is a 48” tall x 60” long vinyl sliding window with double pane insulated Argon filled glass from Lowes. This type of window and the heated air, keep the window from frosting up. You could use a smaller window; I went with a taller window to get a steeper angle for the snow to slide off and also so that I don’t have to bend down to look in the pond. It’s important to build a solid frame around the window so that it does not flex and break the Argon seal. Once the window is framed, you can position it anywhere you want to. I used 2'x6's angled down across the pond and 2'x4's on the bottom to secure the window in place.

For the covering, I switched to bubble wrap from www.SolarCovers.com, it's their Crystal Clear Solar Cover and it's available in many large sizes. It is 16 mils thick, so it's almost 3 times thicker, yet it is letting enough sunlight thru that I'm still getting green algae on the pond bottom and walls.