koi Pond heating

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