Most people attend my tutorial lecture because they bought a home with an existing pond or are considering the construction of a pond in their yard. The second group is luckier because they still have time to avoid many common mistakes in pond and filter design. The first thing you need to decide before starting to design a pond is what do you really want from your pond? Do you want a landscape feature only? Do you want the sound of moving water from a waterfall to add sound to your visual treat? Do you want to be able to watch large fish swim gracefully to add relaxation to your view or do you really just want a water garden with plants and maybe some goldfish? Do you want to buy expensive koi to compete in shows for prizes as a hobby?
The answers to these questions are critical before you take the next step so think about them. The consequences of the answers are mostly financial in the cost of building and running a pond. Small water garden ponds, say less than 1000 gallons, may or may not have a waterfall. If they just contain water plants and some fancy goldfish, they do not require 24hr/day pumping of water and do not require a filter. They may have a fountain squirting water to aerate the water for the goldfish or no pump at all. If this is the kind of water feature you really want, contact Van Ness Water Gardens in Upton, CA for their catalog or your nearest water garden dealer for instruction on how to build, properly stock and maintain a balanced water garden.
|Koi Fish From Japan|
The purpose of this lecture is koi ponds although some of the materials and processes also could
apply to water gardens. I recommend koi ponds to be at least 1000 gallons (8.5ft by 4ft with 4 ft
average depth) and they cost more to build than small water gardens. Koi ponds DO require a filter to clean the contaminants the koi put into the water and a pump to feed the filter running 24 hr/day to maintain the bacteria in the filters costing more electricity than water gardens. I will discuss more on cost when we get to the discussion on pumps. Koi will root around plants in a pond to eat the roots of plants and make a mess likely to end up clogging your pump. Plastic baskets are made for floating plants to avoid this problem. Also, oxygenating plants do add oxygen to the water during the day but take oxygen out of the water at night when the oxygen levels are the lowest and also reduce the pH in the pond by addition of CO2 at night. This reduction of oxygen at night is not good for koi with heavily stocked ponds.
So, you want to build a pond for koi. The next decision is how large of a pond. The general rule of koi ponds is “build the largest koi pond the first time that fits into your landscape, budget and koi collection plans”. The larger the pond, the less sensitive it is to small mistakes in water or pond management. However, the larger the pond the more it will cost to build and in electricity to run the pump for reasonable water turn over rate thru the filters. Not to mention the fact, 90% of existing ponds become overstocked with koi for the size of the pond. When you think about it, koi in a wild or natural lake have thousands of gallons of water for each fish. A conservative rule of thumb for koi pond stocking is one 12 inch koi for each 200 gallons of water and each 10 square feet of surface area. You can cheat on the 10 square foot rule by adding aeration of the water with a waterfall or air pump with air stones. You can cheat on the 200 gallons per 12 inch koi by having an oversized or larger filter system for the size of the pond as koi dealers must do to keep very high stocking rates. More on this in the filter discussion.
Koi ponds should be a minimum of 3 feet deep sloping from the waterfall at the shallow end to greater depth at the bottom drain end. 4 to 5 feet depth is better for several reasons. Koi feel less stressed from potential predators and their bodies grow better with greater pond depth. Greater depth yields more water volume. Greater depth provides a more stable water temperature. However, larger and deeper koi ponds make it more difficult to catch koi and koi seem to swim up and down instead of horizontally for best viewing. Raccoons and Blue Herons love fish ponds only 18 inches deep because it is easy for these predators to enter and exit the pond to catch fish. We call these ponds bird buffets. A step in the side of a pond 18 inches deep for water lilies also provides an dangerous entry point for these predators.
Do you want to only be able to enjoy this water feature when you are outside on your patio or do you want to enjoy this feature during the winter months from the warm environment of your home? I suggest the second choice based on my personal experience. So place your pond where you can see it from windows or glass doors in popular living space like dens or kitchens. This will also give you more opportunity to hear fish jumping while trying to tell you there is a problem in your pond like parasites. Local building codes probably restrict how close a pond can be built to the property line (8 feet in my city). You will need a drain pipe to dump water from filters being cleaned to the sewer so figure that into your design.
Yes, you can dump the dirty water into gardens and onto the lawn as long as you never put salt into your koi pond and I can tell you now, you will use salt someday to kill parasites. So plan for a sewer dump. Do not place the pond under deciduous trees with leaves if you can avoid it. If you do, plan to clean the leaf trap or surface skimmer daily. Ponds can be below or above ground or partially both. The ground helps to stabilize the water temperature in the pond so in ground ponds have more stable water temperature. Note- many city codes require locked or self closing gates and doors from homes to the backyard, high fences and perhaps even a wrought iron fence around ponds to keep children from drowning. So check the local code requirements.
Do not place koi ponds where rain runoff can get into the pond from hillsides, adjacent ground or from the roof of your home. Add gutters or French drains to resolve these issues if necessary. How does this water feature fit into the overall landscape plan for your yard? Balance of pond to gardens or lawn is usually important in any landscape.