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 arduous winter
The bottom line is, if you truly want to be successful in this hobby in a temperate climate, you must heat your pond |
Koi are very hardy and can often survive for years in poor conditions. However, young, small and weak fish can perish in the Spring as a direct result of a lengthy exposure to frigid water temperatures
Certainly the effect of enduring cold Winters year after year weakens a fish's constitution and will can be the catalyst for disease. Once your favourite fish is gone, its not coming back, and the rule of koi keeping is that if their is a problem, your best fish will be involved in the mishap
Ultimately, a shorter period of dormancy (2-3 months maximum) and less frigid water temperatures (8 - 12 Celsius) are recommended. This will reset a Koi's biologically clock and perhaps increase its life span as opposed to heating year round
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#1 - Fish Health & Growth
If you have any plans to grow jumbo Koi, then heating is essential. There also comes a point in time when it becomes foolish not to heat. You have invested a lot of time and money accumulating your Koi collection and it has likely appreciated in value. It seems short sighted not to set up a heating system to eliminate the real danger to our fish of prolonged exposure to cold water
#2 - Mature Filter
Your filter system can be operated year round and you will avoid the lengthy Spring seeding process. Better water quality is the result
#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 heated pond, the fish will much more active |
Electrical Heating
Electrical heaters are not an economically viable option in the majority of cases. In a warmer climate when you just want to augment temperatures slightly, then electrical heating may be the best way to proceed. They are much less expensive to purchase than a gas system however running costs are substantially higher. You will require a very large heater, in the kilowatt range to effect any real increase in water temperature. For example in tests I have conducted indoors, 1 watt of heat per gallon of water will only raise the water temperatures about 2 degrees celsius above ambient [and this is indoors, without the windchill factor]. Doing the math one can quickly see how prohibitively expensive this can become with larger ponds in colder climbs
Gas Powered 
It is certainly not Clarke Koi's mandate to discredit other approaches to heating your pond. However, in our experience both of the options pictured right have weaknesses you likely want to avoid. We did purchase a Kozy Koi unit to test as we were considering retailing them. I will not go into a long diatribe (and it is very long) suffice to say tread softly if considering this unit
Gas Powered - Open Loop or Closed Loop?
I prefer an open loop system because they are much easier to fill and monitor. Also think about what will happened when there is a power failure. Will the water drain out of the system or stay in the lines? Closed loops need to be purged of air in order to work properly as they invariably lose some water over time
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Your design has to allow for the inevitably of both power outages and mechanical failures. When these occur during the Winter the potential for freezing and subsequent ice damage is a real possibility. The heat exchanger is the most expensive part of a gas heater so if it gets cracked you will inccur a major repair expense. But even if there is no damage, gettings things operational again when they are frozen solid is a problem
If you are familiar with heater circuitry you could bypass the safety measures in order to get the heater to fire thus melting the ice. This is not an enviable job in frigid weather and you run the risk of melting the core. Of course this assumes there is no damage done to the unit and lines. Ultimately the only fail safe approach is to run the system using propylene glycol aka motorhome antifreeze
Glycol will lower the freezing temperature to under -20 Celsius when mixed with water in a 30% mix. So, if you have a power outage or your pump dies, your heater is safe from cracking. You will also be able to fire your heater up and resume heating your pond once power is restored or the faulty pump replaced. This is key - getting your system back online
key points
So the two main points are not only preventing the expensive damage that can occur by using glycol, but also being able to get your heating system back on-line as soon as possible before your pond temperature drops. There is a downside to running glycol, First, a second pump is required to run the hot circuit. Second, a stainless steel heat exchanger needs to be purchased and setup. And finally, the conduction of stainless steel does not match copper - as a result, heating costs will be higher |
