koi Pond heating

Talk to any experienced Koi Keeper and they will tell you that koi do much better in warmer water without a long term exposure to sub 10 degree celsius temperatures. In Toronto, good growth water temperatures [those over 20 Celsius] are only maintained for about 4 months of the year ! We have hot short Summers that often don't get started until late May and are cooling down by mid-September

The result is that fish often succumb to the cumulative effects of these long arduous Winters. The bottom line is, if you want to grow jumbo koi and ensure their long term success, you must heat your pond

Benefits of pond Heating

#1 - Fish Health & Growth

If you have any plans to grow jumbo Koi, then heating is essential. Unfortunately our Winters are long in cold here in Toronto and in many other parts of the World. I find the cumulative effects of surviving that hardship eventually catches up to fish and one Spring they are not their to great is

#2 - Maintain a Mature Filter

Your filter system can be operated year round and you will avoid the lengthy new pond syndrome as the filter bacteria need to ramp up once again. This can easily take 2 months! The result - healthy happy fish instead of weak fish potentially exposed to poor water quality

#3- Personal Enjoyment

You will enjoy your fish for a much longer season. During April in Toronto it can be 5 degrees one day and suddenly jump to 25 degrees the next. In a controlled environment, the fish are not subjected to these extremes and can be regularly fed

One of our clients who heats also keeps his tropical plants outside in the greenhouse. They are massive as a result, and throw away annuals are the perennials they were meant to be
  • Hookup to your existing gas meter and gas line needs to be run
  • My personal experience with this type of heater was not good
  • The tank and piping should be fully insulated to avoid heat loss

Pond Heating Options

Electrical Heating
Electrical heaters are usually not an economically viable option in the majority of cases due to the high cost of hydro. In a warmer climate when you just want to augment temperatures slightly, then electrical heating may be the best way to proceed as the cost of entry is far less than gas powered heaters

You will require a heater in the kilowatt range to effect any real increase in water temperature on all but the smallest ponds. For example in tests I have conducted indoors, 1 watt of heat / gallon of water will only raise the water temperatures about 2 degrees celsius above ambient and there are a lot of variables. Doing the math one can quickly see how prohibitively expensive this can become with larger ponds in colder climbs

Gas Powered
From a running cost perspective, gas heating is the most economical. Expect to pay at least $3K for a basic heater and gas line setup. This is an investment for sure but when you factor in the value of your koi, everything is relative. There are several factors to consider of course, for example, the composition of the heat exchanger and the method of heating whether it be a pressurized boiler with heating coils or flow through pool type heater

Boiler or Pool Type Heater
Having used a specialty closed loop koi heater for a year, I have to say the experience was awful. It was a closed loop boiler and lost a bit of water over time. Trying to fill the lines up in mid Winter is not ideal. If you choose to use a pool heater, then you have 2 options. 1 is to run the water through the heater or set up a separate heating loop, isolated from the pond. Each option has its disadvantages and advantages

Running through a Pool Heater

While copper is the most efficient conductor at about 80%, it is also toxic to fish in higher concentrations. Salt encourages Cu to become soluble and so does soft water. If there is a power failure, the change of the heat exchanger cracking in the Winter is possible. If it doesn't crack, then it may freeze up. Getting the system back online then, after a power or equipment failure, can be difficult. You can pay more for a cupro nickel or stainless exchanger which help with the copper issue in the pond

I have one client who has run a pool heater with no modifications for 15 years. No visible effects on the koi with the Cu heat exchanger and never a problem in the Winter. He enjoys less costly setup and running costs. with a second client, we setup a separate heat loop, with an external stainless steel heat exchanger. When he had a power failure, there was no damage to the heater due to the 10% propylene glycol mix which stops freezing. We were able to get the system back online fairly quickly

The separate exchanger method provides the security of knowing nothing will freeze and there will be no copper in the pond. However, it does cost more to setup with the additional heat exchanger, tank and pump. I guess you can look at it as an insurance policy

Naturally if you are going to heat, you need to have a greenhouse covering or there will be too much heat loss

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