Should I heat my Koi Pond?
Some people heat their ponds all winter, some don’t heat at all.
I use my pond heaters to keep the temperature stable, Koi will tolerate cold water for long periods but they don’t like rapid changes in temperature.
This last winter, the coldest we have had for a long time I heated the water to around 9-10 degrees C.
I don’t heat during the summer, I start heating around November when I put the covers on (to cover the pond I use conservatory type roofing panels, very strong and good insulation – they are quite expensive but once bought they will last)
The purpose of my heater is to keep the pond at a reasonable temperature and don’t expose the fish to the harshness of winter, this next year now the fish are older and have been in the pond a long time I am going to go down to about 7-8 degrees C in the coldest times.
Electric Pond Heaters
This is my Elecro inline heater – its rated at 2KW, roughly they say 1KW per gallon of water.
I tend to use this more in the really cold weather – I have now switched over and use an air source heat pump (below) – this is always set a couple of degrees lower than the heat pump as a backup – I can use it as an additional heater if the weather is exceptionally cold.
Heating with an Air Source Heat Pump
Above: My second heater – an air source heat pump, and next to it the pipe arrangement with bypass valves
These units are designed for swimming pools however they are becoming more poplar amongst koi keepers – this model is a Duratec Dura+ 7KW, it takes 1.2KW of electricity and can give you up to 7KW of heat – This however all depends on the air temperature.
They work using the refrigeration cycle, it absorbs heat from the surrounding air, and transfers it to the water, the air out of the fan on the unit gets very cold!
This model can work down to -10 degrees C, if the coils at the back freeze up it switches to an automatic defrost cycle, clears the coils of ice and then carries on heating.
These units are best when it is warmer weather, the colder it is outside, the less heat you get out of it – however this is all dependant on what temperature you are heating to.
Keeping your pond at 10 degrees C the unit will cope very well, even in cold weather.
I do use this during the winter but the best time for me to use it is March-May time, when the air outside is warmer, the unit dosn’t freeze up and is much more efficient at heating the pond.
During the spring I have the thermostat set at 13-14 degrees C, heating in the spring helps stop rapid temperature swings because it can get cold at night but hot during the day.
This heat pump has an easy to use control panel, has an on/off timer and it can also cool as well as heat, or use the automatic function to keep the water at the temperature you set, extremely quiet when running, which has to be a consideration when locating devices such as this. I purchased this heat pump from http://www.heatpumps4pools.com
Above: Control panel of the Duratec Dura+ Heat Pump
How much does it cost to heat my pond?
Forgetting the cost of the heater itself, there is the running cost to consider. Electricity is the easiest way to heat your pond, the heaters are easy to install and readily available, some use gas to heat and either use home centeral heating with a seperate zone or a seperate gas boiler.
The air source heat pump is a lot more efficient than my Elecro inline heater – the input power is 1.2KW, and according to the COP graph, at 0 degrees C outside, and keeping the water at 13 degrees C you can get around 4KW of heat into the water.
Its hard to compare the cost of running the heater, I have a DIN rail mounted electric meter installed in the electric panel for the pond, so I can pay for what I use. This winter I had a growing on setup in the greenhouse with a 1KW heater and a 280W pump, I have now shut this down, so that will have had an impact on my electricity use.
The weather is different every year, but this year, the coldest winter for a long time, I only had to switch back to the Elecro heater during December when we saw temperatures of -11 degrees C, other than that it coped very well heating my pond.
Should I heat my pond?
Yes is my answer – Koi are expensive, this is an expensive hobby so why save on electricity if it could risk you losing your fish?
I don’t go mad with the heating, and I am happier when it dosn’t come on but its there to keep the fish alive, and the cold we have had this year 2010-2011, I would have probably lost the lot if the pond wasn’t covered and heated, keeping the heat, even low stops the pond freezing and koi more active than just slumped at the bottom.
The fishes immune systems don’t function well under 12 degrees C, this is a problem in the spring because all bacteria, parasites, viruses and fungi that might be floating around start to wake up and could cause problems for the fish, the rapid swings in temperature are also no good for them.
I keep my heater on about 13.5-14 deg C just to stop this from happening, also keeping the water above 12 degrees C.
You cannot avoid temperature swings, the sun comes out and can add 4-5 degrees to your water, then it will drop at night – this change is very slow and even slower with more water you have.
Heat Pump Installation
