Quote:
Originally Posted by
JasPR 
Here ya go Mike— simple enough?
Every living thing has fundamental requirements to live a normal healthy life. Most people understand this instinctively and would not try and keep a Great Dane in a two bedroom apartment or a horse in a car port.
But when it comes to our fishy friends it is not always so obvious to the new pond owner. We do know not to try and keep saltwater angel fish in fish bowls but things getting trickier for most when assessing the needs of one pond fish over another.
I’d like to talk about koi for a moment. Everyone can envision a tranquil oriental styled pond filled with the splashing colors of the exotic Japanese koi. But do you know what koi need to live the long life they are legendary for? Is it the same need as the little goldfish we all grew up owning? The short answer is , No. And even though many have imagined the goldfish and the koi as being one in the same, they are quite different in their needs.
The goldfish is a highly adaptable creature, living in shallow water of minimal quality and quite happy in a water garden setting. Their small size and hardy nature allow then to live among the plants with only a small filter or waterfall and moderately running water to provide for oxygen needs and ammonia removal. Water gardens with sloped sides and depths of 10 inches to 36 inches are fine. And water turn over as infrequent as six times a day will be adequate to keep one goldfish per 20-25 gallons of water. Some of the common varieties of comets can be quite attractive and the bright red/orange, the sarassa comet ( red and white), the true yellow comet and the blue shubunkin ( calico comet) should be able to satisfy even the most color hungry pond owner! These hardy fish require only minimal care and are well suited for the average water garden and backyard pond of 50- 2000 gallons.
The koi pond is a completely different type pond however. And this due to the fact that koi are completely different fish than goldfish.
Typically build with straight walls, these 4 feet plus deep ponds ( 5- 6 ft deep being ideal) are designed with the requirements of a much larger fish in mind - the koi. The perspective koi owner must know that the koi they see in the pet stores and garden center is the ‘baby version’ of a koi, and typically only in the first year of life. Adult koi, if allowed to grow to full size without stunting them ( a practice deemed cruel by many established koi keepers) is a minimum of 20 inches long, with 28 inches or large being common. So these are powerful fish known to be strong swimmers and great jumpers who can easily launch themselves from the sloping sides of a garden pond. They also benefit from a pond environment where they can swim up and down as well as across the pond. The depth of the pond allows them to feed off the top as well as forage off the bottom of the pond. The depth also provides other benefits which we will discuss in a moment–
Koi are intensively bred for their colors above hardiness and are not as strong as the sturdy goldfish. As a result, they require better water conditions along with more stable water conditions. Again, a large volume of water extending deep into the soil insures more stable water conditions and water temperatures and guards against changes created by large rainfalls and chilly night air.
And as large active fish , koi are also MUCH messier fish than their tiny goldfish cousins. They love nothing better than to root out the soil in planters in search of worms and other insects. And they have ravenous appetites. All this requires a good filter of considerable size and also a water current that will discourage any of the koi’s handiwork from settling to the pond bottom to decay and cause pollution. And of course, as large animals the amount of personal waste produced is considerable. To facilitate this waste removal all modern koi ponds must come equipped with a drain at the bottom of the pond. And as the pond gets larger ( 5,000- 12,000 are ideal size ranges), several drains may be used to insure both adequate water flow to the filters and a good continuous sweeping of the pond floor. The frequency of the ponds flow rate through the filters is also very important. Ideally, all the water in a koi pond should move through the prefilter and biological filtration system a minimum of once every two hours. This guarantees that water will be exchanged throughout the pond and that waste will be carried to the filters as the koi produce it.
As koi and biological filters benefit greatly from maximum oxygen levels in the water, a turn over rate of once every two hours guarantees a mixing of water and frequent contact of that water with the surface where oxygen enters the system most readily.
This article is meant to present some basic differences between a water garden feature/ goldfish pond and a modern koi pond and is not intended to be a complete ‘how to’ on koi pond building. Details of filtration vary but basic principles are included in the variations.
Garden pond and koi pond comparison:
Garden pond - small, typically 100- 3500 gallons
Koi pond - large, typically 3500- 12,000 gallons or larger.
Garden ponds- natural or formal design. Often bowl shaped with pebbles in the base. Slopped sides and typically with a depth fo less than 3 feet.
Koi Pond - natural or formal with straight sides and of a greater depth with 3 feet being minimum with depths of 4- 6 being most common.
Garden ponds- lightly filtered with biological filters incorporated in simple inpond filters, skimmers or within an artificial waterfall. Plants are part of the setting.
Koi ponds- heavily filter with extensive use of bottom drains, skimmers, prefilters, biological chambers and large high circulation pumps and associated plumbing to accomplish required turnover rates. Plants are typically absent in a koi pond as the water is deep and fast moving, a poor environment for most blooming plants.