how to: setup a greenhouse covering for your pond

Living in a temperate climate means water temperatures are not conducive to Koi growth on a year round basis. In Toronto this typically means fish stop eating in early November and likely don't begin eating again until mid April

I highly recommend heating, but it is not for everyone. Constructing a greenhouse however, is an easy 1 - 2 hour job, is inexpensive and provides a huge benefit to your fish

Key Benefits of a Pond Greenhouse

You can expect to begin feeding a couple weeks earlier than normal as well as feeding your Koi later into the Autumn with a greenhouse. In fact, here in Toronto, most clients have had no ice on there ponds whatsoever with just a greenhouse covering and bubbler

If you put your greenhouse up early enough, it will stop any leaves from getting into the pond. Additionally, your koi are visible throughout the Winter instead of being under ice. This is key if there are any koi health concerns
  • As ponds get wider, the greenhouse must be tallerto allow for the proper slope and consequential run off
  • For ponds with lots of rock, a lean to cover can work with sufficient slope

pond cover Materials List

  • 1.25 inch gray electrical conduit - for hoops - comes in 10 ft. lengths, this is the best diametre because it is strong but still flexible. Place 3-4 feet apart. For ponds 5-6 feet wide, 1" conduit can be used

  • 0.75 inch gray electrical conduit - for cross support, 10 ft. lengths, affix to the 1.25" conduit with duct tape at the top peak of the hoops

  • 0.75 inch hollow metal rod - come in 10 ft. lengths, cut in half and used to anchor hoops

  • Rebar - 8 foot - cut into half, to anchor 0.75 cross support conduit

  • Super6 6 mil. greenhouse poly - do not use vapor barrier or utility plastic, it has no UV resistance. 1 solid piece needs to used or it will be blown apart by the wind

  • At least 2 people - although it can be done, it is difficult going solo

  • Post Pounder - to easily drive in the metal rods without damaging them like you would with a sledgehammer

  • Ladder / Plank - for larger structures, you will need to go out over the pond to tape the cross support conduit to the hoops

  • Duct Tape - to tape 3/4" cross support to the 1 1/4" hoops. [some have used plastic ties, criss crossed, with success]

    • This post has been damaged by a sledge hammer. A post pounder [in the background] is the way to go
    • A QSR Zipper sticks onto the poly and an opening is cut
    • It allows for easy access to see your fish


  • After the metal rods are in, bend the 1 1/4" conduit into hoops
  • The 1.25" conduit slides down over the metal rods
  • Duct tape is used the attach the 3/4" conduit to the hoops
  • The conduit frame should have a nice slope for effective runoff
  • Cover with 1 sheet of greenhouse poly, anchor with stone
Tips:
The overall design concept is one of flexibility and slope. This alllows the cover to move with high winds and snow and rain to run off. Assembly and reassembly is quick and easy

If you hear the conduit "creaking" as you bend it onto the rods, it is not seated together properly. Remove and insert fully

pond Greenhouse setup video

  • Snow cover will impede solar heating
  • Even at a chilly air temp of 10F with no deicer, ice has not formed
  • The greenhouse is brushed off to let light [heat] in