We've accidently left goldfish that were hiding in above ground water lily displays and some survived under thick ice. Definitely more cold hardy than koi. We try to remove all from displays before winter. Small koi in the same situation never make it and are dead when the ice thaws. Read one study that carp can survive 33F water but it's not clear if this has negative effects and slow recovery. Common thought is that exposure to temps below 39F causes weakened state and less resistance to bacteria infections and diseases. 39F is the typical minimum temps carp experience in lakes and rivers deep water and this is the low temp they evolved at. Tank cleanliness and water quality also big factors for over wintering.
Last edited by batman; 02-08-2022 at 08:22 PM.
The real Batman wears polyester! Don't be fooled by the plastic imposter.
Put the foam on the outside of the block.
My koi pond in Charleston, West Virginia, provides possibly useful information for this discussion. This is a 4000 gallon pond system, with about 50 koi of varying size.
I cover the pond early December with a homemade greenhouse constructed out of heavy duty one inch PVC pipe and 6 mil clear green house plastic.
The filter system runs through a bottom drain to the entrance of a six foot diameter 6 foot tall vortex settling tank, water exits this tank by gravity to an on line pump. The on line pump delivers the stream to a pump house where it runs through a bead filter to an 80 watt UV light then to a waterfall built on the side of the pump house to drop the water back to the pond.
The 4 inch pipe from the bottom drain to the settling tank is partially buried, but with sections exposed as the water enters the settling tank. The exposed sections are insulated but not heated.
The 2 inch pipe from the settling tank to the pump is heated with automatic heating tape, with insulation over the heating tape.
No heating or insulation for pipes or bead filter or UV light in the pump house, but a little heater avoids freezing temperatures there.
During the colder spells this Winter measured water temperatures in the circulating system have been in the 35F to 37F range for weeks at a time. The koi do well through this arrangement. The pipes don’t freeze. Daily highs in the 20’s lows in single digits.
This has been my experience the last several years.
The stand of Watercress growing in the waterfall stays green and growing all Winter, which amazes me.
Last edited by Roddy Conrad; 02-14-2022 at 02:09 PM.
Your koiphen chemist and environmental scientist.
yes this is another reason why i shut my pumps down in the winter. there are many other issues that could happen and its just too **** cold to be messing with water in the winter. and honestly, after the work i do in the spring, summer, and fall i can use a break with pond maintenance so its nice to throw in a strong bubbler and a surface heater (when needed) and walk away.
I understood that if my pond was at least 4' deep the koi will be fine over the winter. I plan to go 6' because overkill is its own reward. This week, finding out that ice on local lakes is 2', I'm not sure 6' is even overkill.
I planned to make it so that all my plumbing was angled/sloped and I could disconnect it before the filtration. Then I put on an air fitting and valve, hook up the compressor until air comes out the bottom drains, and then close that valve until spring, leaving all the plumbing full of air. I figured air will not burst the pipes. The drain out all the filtration and wait out the winter. This will be my first koi pond so I maybe totally wrong with this idea.
That is what I do to my pond each winter.
Gently replace the water with air in each pipe and then shut the valve, and wait for spring. I am a few inches over 6ft deep
I have found that pushing water out of pipes only works in certain conditions, once the air has a path thru a larger pipe (3 or 4"), like the top 1/2" of the pipe, the air flow stops moving most of the remaining water. If you use a large volume of air compared to the diameter of the pipe (1/2" or so) and cycling it on and off long enough, you can push most of the water out. Just adding air until it bubbles out the bottom drain will not clear that drain line. That bottom drain pipe depending on its slope will be full of water once the air is turned off and all the water pushes that 1/2" of air back up the pipe towards the valve. Also, over time, some air will be absorbed into water, and the water level in the drain line will rise. If the valve on the drain line is deep enough, you may be ok.
Just a bump on this thread. We recently had below freezing temps and here is what happened to one of my 3 barrel bottom drain valves. I think sitting water in the ball valve expanded and pushed it apart. Luckily I got home in time and still had about 12-16 inches of water left in the pond. No casualties.