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 late October and don't begin eating again until April
I do 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
You can expect to begin feeding a couple weeks earlier than normal as well as feeding your Koi later into the Fall with a greenhouse. In fact, in milder winters here in Toronto, some clients have had no ice on there ponds whatsoever with just a greenhouse covering
Besides heating the water up about 5 degrees, another huge benefit is is eliminating leaves getting into the pond if you get your cover on before they drop
There are many ways to construct a greenhouse. We feel this is one of the better methods when you consider cost, erection time, storage and net benefit. For structures larger than 16-18 feet wide for most of the greenhouse, a proper metal greenhouse structure is advised
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This pond, typical of a smaller landscaper pond, is really too shallow to expect success year after year without a Winter covering
The pictures below illustrate the covering of this particular pond |
This pond has been covered every Winter since 2000 and has never collapsed. Notice there is no snow buildup as it easily runs off
Gary heats his ponds and his tropical Cannas survive the Winter inside the greenhouse. As a result, they are massive |
As ponds get wider, the greenhouse must be taller. This is essential to allow for the proper slope and consequential run off
Ponds larger than 15 feet wide become more difficult to cover using these techniques and are more prone to collapse |
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- 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
- 0.75 inch gray electrical conduit - for cross support, 10 ft. lengths, affix to the 1.25" conduit with duct tape
- 0.75 inch hollow metal rod - come in 10 ft. lengths, cut in half and used to anchor hoops
- Rebar - 3 foot - small size diameter for support beam anchor
- Super6 6 mil. greenhouse poly - do not use vapour barrier or utility plastic, it has no UV resistance. 1 solid piece needs to used
- 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
Please note - the cover is designed to be flexible and facilitate runoff. You need to have 1:2 slope to avoid ponding (if the cover is 15 feet wide, the cover should be almost 8 feet tall at centre). Side supports are not generally recommended as these easily create ponding pockets. Read over all instruction before you begin
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The metal rods are cut in half to provide 5 ft. stakes. Stakes are driven about 1 - 1.5 feet into the ground, on a slight angle towards the pond. Use a post pounder. Do not drive the stakes too far in - you want to remove them next spring and once the ground freezes, they become very well anchored anyway. Before you drive them in, lay them out so that out can comfortably avoid any obstacles
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Place the posts no more than 4 feet apart. If you have a lot of snow in your area, 3 foot my be a better distance to space the rods. Attach 2 of the 1.25 inch conduit pieces together making sure to seat well. Consider a couple wraps of duct tape over the joint. Slide one end of the joined conduit over a rod and then the other over the opposite rod. The key is to facilitate runoff. Therefore, the rise/run ratio should be 1:2. ie. rods are 15 feet part, (greenhouse width) the center peak should be about 8 feet high
Try to create a lengthwise slope as well by having the structure taller in the middle (creating a dome effect). You will likely have to cut some of the conduit to size it properly. Large ponds may require 3 pcs. of
conduit per hoop in the centre. This is the limit and the taller you go, the greater the chance of a collapse |
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Once all your conduit hoops are in place, use the 0.75 inch conduit to run down the center line of the greenhouse. Anchor this by sliding it over rebar driven into the ground at each end. Affix the 0.75 conduit to the 1.25 conduit where they cross with duct tape. Do the best you can, it won't be perfect but it doesn't have to be. The 3/4" conduit helps stabilize the conduit hoops vertically. When you tape it to the hoops, have someone eyeball it so that the hoops are as vertical as possible |
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Caution - Do not affix any side support conduits on the structure. This will create collection pockets of water/snow which will likely grow and collapse your greenhouse - called "ponding". If you do choose to add these extra support, you much diligently check the greenhouse, even so an overnight rain could still collapse it
Caution - It is imperative to use proper greenhouse poly. Vapour barrier will break down quickly and is not large enough. You need to use 1 solid piece of poly - if you use pieces they will get destroyed by wind and not last the Winter . Greenhouse poly comes in 24, 32 and 40 foot widths x 100 piece rolls. We sell it by the liner foot in the mentioned widths |
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Once the poly has been stretched over the conduit frame, pull it tight as best you can and anchor with rock, patio stones, wood, buckets of water etc. I don't recommend cutting the poly to create a door, rather move a couple of rocks aside and pull the poly up to enter. Don't forget to allow for an area inside the greenhouse so that when you enter it, you can stand comfortably
This greenhouse took just over 1 hour to erect with 2 people and the cost of materials was $300.00. You can expect to reuse these materials for at least 5 years. Good Luck !
Tip - don't take your greenhouse down the first warm day in April. We recommend leaving it on until the first week of May |
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Left
top centre joints are best connected with a few
wraps of duct tape
Right
A solar blanket is a worthwhile addition in both a heated and unheated covered pond. They help trap heat and reduce heat loss. A couple cautionary notes, keep an eye on the O2 levels and fish sometimes jump on the blanket. To avoid this, bring the end of the blanket up from the pond at a 90 degree angle for a couple of feet and tie it off
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If you would like us to set up your greenhouse for you, just give us a call. If you prefer to do it yourself, we sell the Greenhouse poly that you should use. Other components are available at any big box store ie. Rona |
