THE INS AND OUTS OF KOI POND BUILDING
by Mike White, White Water Filters

PART 2: Design

In this series of articles I will not endorse any brands or manufacturers. I may talk about different manufacturers but if I don't mention a particular company it in no way implies that I feel a product is inferior or doesn't measure up. I will tell you what I would look for in a product. If a product meets the criteria I use, does not imply that it is the best, only that it meets the specifications I am looking for. All opinions expressed are my own.

This part will discuss pond design. The first item is the shape of the pond. In the first article I talked about the sized of the pond. The ideal shape is a perfect oval, however most people don't construct a pond in a perfect oval. Why is the perfect oval ideal? This shape provides the best possible water circulation in the pond. The cross section of the pond should reveal a bowl shape. The bowl shape provides a good way to get the debris to the bottom drain. Once again, I am speaking of the "ideal" shape.

Now that we know what the ideal shape is and why it is considered such, you can work on determining the compromises you are willing to make to result in the aesthetic design you want.

There is more to pond design than size and shape. There are various pieces of equipment on the pond, circulation of the water and filtration equipment to be used.

Circulation of the pond is how the water moves through the pond. Our koi ponds are not stagnant pools but closed systems of circulating water. Water circulation can come from many sources, such as waterfalls, streams, jets, and return pipes. All the moving water is a result of water being moved by pumps.

Ideally the pumps should move the entire volume of water once per hour. In addition, "ideal" circulation would mean every drop of water in the pond is in constant motion. Most ponds accomplish water circulation through the use of waterfalls. If we are talking of the ideal way of moving water, this is actually the least preferable. Waterfalls can drastically affect the temperature of the water and bring large amounts of debris in. Waterfalls also attract birds, bringing additional undesirable elements into the pond in terms of parasites, waste, etc.

Water circulation can also be achieved through the use of air injected into the water. Air is the most efficient way to move water.

I have yet to see a pond with ideal circulation. Most ponds have very poor circulation and this can be a major cause of problems. The movement of water is very difficult to see at best or impossible. The use of a dye or colorant can help illustrate how the surface of the pond circulates. The reason I say "surface" is because when the water has colorant in it, it makes it hard to see through the surface to the water lower down.

Next I would like to address devices that allow water to be moved outside the pond. The first of these is a skimmer. The purpose of a skimmer is to remove surface debris. The first skimmers used on ponds were swimming pool skimmers. About 10 years ago a company called Aquascape Designs incorporated the design of swimming pool skimmers into a larger container. With the use of a net instead of a basket, more debris was allowed to collect before the skimmer became full. Approximately 6 years ago Pond Supplies of America radically changed this design. Instead of using a swimming pool weir, they used a device they call a bellows. A weir is supposed to take the water just off the surface of the pond. A swimming pool weir is designed to allow water to enter the skimmer not only from the surface but also to a depth of about 5 inches. This decreases the efficiency of the weir. Pond Supplies of America designed their bellows so that only the surface water is taken into the skimmer, improving the efficiency of the skimmer. Since that time, there has been an explosion of skimmers on the market; some good and some not so good.

When looking for a skimmer one should inspect how the skimmer is built. A skimmer is typically buried in the ground. The pressure of the dirt around it tends to deform the skimmer unless it is built strong enough to withstand this pressure. When the skimmer is deformed (misshapen), it cannot operate properly. Most modern skimmers have a net or basket to catch large debris and then a polyester pad to catch finer debris. These units provide mechanical, not biological, filtration. This means they mechanically remove debris from the water. Don't worry about using chlorinated water to clean the net, basket or pad. Expect to have clean these items. The better they are working, the more often they will need to be cleaned. Recently brushes have been added to skimmer design to catch more debris. The vast majority of debris in a pond comes from outside sources such as leaves, seeds and pollution in the air. Of course I am talking about outdoor ponds as most ponds are located outdoors.

In the next article I will discuss other devices that move water outside the pond, pumps, and returning water to the pond.


Part 1 - Planning a New Pond || Part 2 - Design || Part 3 - Circulation || Part 4 - Mechanical and Chemical Filtration || Part 5 - Biological Filtration || Part 6 - Biological Filters - Mats, Pads and Biofalls || Part 7 - Biological Filters - Bead, Tower and Vortex Filters || Part 8 - Fluid Bed, Bio-Reactors and Nexus Filters || Part 9 - Planning for Pond Expansion

©2004 all rights reserved to Mike White