2torial #0693:
Learn2 Build a Garden Pond

There's goldfish in them there ponds

If you're searching for a way to make your backyard a little less like, well, a backyard, how about adding a pond? With the right tools, it's easier than you might think, and the rewards are well worth the effort. With a few aquatic plants and a school of goldfish, your yard can become a magical, miniature ecosystem--the perfect spot for you to relax, and for a variety of wildlife to set up a home.

There are many types of man-made ponds--from concrete- or fiberglass-bottomed constructions to ponds with electric water filters and pumps. This 2torial explains how to set up a non-circulating pond using a flexible pond liner, with goldfish as the primary inhabitants (other outdoor fish, such as koi, require special pond features not outlined in this 2torial). Non-circulating means that the pond's water isn't mechanically agitated--and therefore oxygenated--with a pump. Rather, the water is agitated and oxygenated through a variety of aquatic plants.

The main benefit of a non-circulating pond is that you don't have to install and maintain a pump and filter system, which can be expensive and time-consuming. The drawbacks are that the pond can safely sustain only a limited number of fish (depending on the water volume), that the water quality isn't as clear as ponds with pumps and filters, and that you'll have to perform some regular water maintenance. However, if you build this type of pond, you can add a pump and filter later on if you want. Consult an outdoor aquarium supply store for possibilities.

Note: Be aware of building codes and property laws in your area. Consult your local planning commission to see if any permits or fees are required to begin construction.

Choose the site

The more preparation you put into choosing the right site for your pond, the easier the later work will be. When you start looking around your yard, here's what you want to consider:

• High, level ground is key. If the pond is built on a slope, it'll need a retaining wall. If it's built on low ground, such as at the bottom of a slope, there's a risk of ground runoff (water running under or on the ground surface; from a heavy rain, for example) contaminating the pond water.

• The location needs at least 6 hours of sun each day to support the plants. However, too much sun (more than 9 hours) can cause problems.

• Think twice before situating the pond under a tree. Dealing with the roots will probably triple your digging time, while falling leaves will have to be regularly skimmed off the water.

• Consider the view from your house. Do you want to be able to see the pond from a particular room?

• Finally, be aware of any possible underground pipes, cables, septic tanks, and so on. Consult your property survey or call your utility company to be sure there are no obstructions.

Design the pond

Once you've found your spot, it's time to figure out what the pond will look like:

Shape. Most pond shapes tend to fall into two categories--formal and natural. Formal ponds are typically rectangles with a regimented edge of set stone (think of formal European gardens). Natural ponds can be any shape, usually with a shoreline of different-sized stone. Try to find a shape that fits the natural contours and overall design of your landscape.

Surface area. Unless you have access to mechanical digging equipment, like a backhoe, you're going to be moving all of that dirt yourself, so keep the scale manageable. A reasonable starter size is about 15 to 30 square feet (1.4 to 2.7 square meters).

Floor and tiers. The depth of the pond must be at least 2 to 3 feet (61 to 91 centimeters). The sides should rise in tiers, or steps, which encircle the floor (instead of being vertical). You'll need at least one tier below the water's surface (usually about 1 to 1.5 feet, or 30 to 47 centimeters, above the floor) to support plants and rocks. Each tier needs to be a flat, level plane.

Shoreline. Plan for another tier just above or below the water's surface to act as a shelf for the shoreline of rocks and gravel. For more details on creating a shoreline, see Step 6.

When your design is complete, mark the pond's outline on the ground by using spray paint (this works well for a curved shape--spray along a hose edge), or stakes and string (better to outline more formal designs). Include the shoreline area if it will be recessed.

Dig the pond

Time to get dirty. From the edge of the original outline, dig down at a slightly sloped angle (about 15 degrees) either to the shoreline depth, or to the depth of your first tier. When you reach the depth of the first tier, clear out all the dirt--the tier should be fairly level all around. Mark the tier's inner edge with another spray painted or staked-and-strung outline, then dig to the next tier or the floor, again at a slight angle. As you dig out the center of the pond, keep its floor roughly level.

Note: Clear out any roots or rocks as you work. Objects protruding into the hole can tear the pond's liner, which can lead to water drainage and contamination. If you're having a hard time removing a particular object, you can pad the area to create a buffer between the ground and the liner. Outdoor aquatic supply stores sell polyethylene padding material, but dampened newspapers, old pieces of carpet or carpet padding, or a layer of wet sand work just as well.

Finally, if you're wondering what to do with the big pile of dirt you've just created, leave it for now. You may need to use some of it to build up certain areas of the pond.

Line and fill the pond

A liner will help make your pond a relatively contained ecosystem by preventing water from draining into the surrounding soil, and earth from eroding and contaminating the water. Here's what you need to know regarding choices, size, and installation:

• Buy a liner specifically made for ponds (look under "aquarium" or "aquatic supply" in the phone book, or type it into your search engine). Other plastic or rubber materials can contain chemicals that will harm fish and plants.

• The liner length should equal the sum of the pond's length (including the shoreline), plus twice the pond's depth, plus an extra 2 feet (61 centimeters). Use the same method to calculate the width. If you have an irregularly shaped pond, use the maximum length, width, and depth in the formula.

• To install the liner, unfold and lay it evenly over the hole. Gently push it down to the pond's floor, then partially into the recess of the tiers (you don't have to push the liner tight against the surface; the water will take care of that). Be careful not to cave in any of the sides--using a broom to push in the lining will help you keep your distance from the edges. Place a weight (like a rock) on each corner of the liner, so it won't accidentally slip in when you add water.

• Lay the hose on the bottom of the pond and turn on the water. Make any necessary adjustments (unfolding kinks in the liner, and loosening it if it looks like it's stretching too much). Stop when the water level is about a foot (30 centimeters) from the surface level to allow room for rocks and plants.

Note: Much of what you'll put into your pond--including the amount of fish, water conditioners, and biological supplements--depends on how much water it holds. To calculate this volume, time how long it takes to fill it, from the first drop to the last. Then time how long it takes to fill a gallon (or liter) container using the same hose and water pressure. Divide the first time by the second time to determine volume.

• Once it's filled, trim the liner with scissors or a sharp knife, so its edge is a foot (30 centimeters) past the outer edge of the shoreline. Keep weights along the liner's edge so it doesn't slip in.

You're almost ready to start decorating. If you used tap water to fill the pond, wait a day before adding any plants. This time will allow the chemicals the water is treated with to partially evaporate.

Add the stone and plants

Time to make this plastic-lined hole in your yard actually look like a pond:

Add the stone. Smooth, rounded stone (called river rock) works best. Avoid using rocks with sharp and jagged edges under water, as these can tear the lining. For a formal pond, you'll probably want same-sized flagstones--flat, rectangular stone (see Step 6 for more details). For a natural pond, try a mix of sizes. Lay some stone along the tiers and floor in between the plants (you may have to get in the water), in whatever pattern suits you, then move on to the shoreline.

Add the plants. You can find freshwater oxygenating plants in outdoor aquatic supply stores and at some garden stores. Describe your project so the seller can make recommendations. You'll want to buy both submergent plants (which sit entirely underwater) and emergent plants (which are partially above water--water lilies, water hyacinth, and duckweed, for example). The plants are either free floating or come with their own submersible containers. Set them under water, mainly on the tiers, but put a few submergents on the bottom as well.

Note: The stalks and leaves of emergent plants need to cover at least 60 percent of the water's surface. Without them, the water can become overheated, stagnant, and completely inhospitable to fish.

Also, it can take some time for the plants to balance out the water's chemistry (the water may turn a little soupy with algae at first). But don't worry, if you have enough plants, they'll eventually be able to clear up the water. The time it takes can range from a few weeks to a few months.

Create the shoreline

Technically, the reason to create a shoreline is to cover and help secure the lining's border. Aesthetically, though, it can do wonders for blending the pond into the surrounding landscape. Keep these guidelines in mind when creating yours:

• Always bury at least 6 inches (15 centimeters) of the liner's outer edge. This will keep it out of sight and prevent it from slipping into the pond.

• Situate rocks so they extend over the water's edge about 1 to 2 inches (2.5 to 5 centimeters). This will help further camouflage the liner.

• For a formal pond, try laying flagstone side-by-side along the shoreline perimeter (and the tier), or stacking the stones up from the underwater tier until they reach past the surface, then tucking the liner underneath the top stone.

• For a natural pond, the shoreline can be built up from a shallow tier, or started above the water's surface. Mix large and small stones for a more organic look (use aggregate--washed bits of stone--to fill in the gaps).

• Arrange plants along the shoreline in their pots, or cut a hole in the liner (at least 6 inches, or 15 centimeters, from the water's edge) and transplant them. You can also create a gravel planting pocket by stacking a wall of stone along the edge of a tier, then filling it in with aggregate above the water level. Bury the pot in the gravel to its top so it's level with the aggregate and above the water level.

Add the fish

When you add your fish, remember that you're creating their entire world. If one element is off, the whole system can be affected. Follow these safety tips for a smooth introduction:

Prepare the water. As mentioned earlier, most tap water is treated with chemicals. Some of these chemicals (particularly chlorine and chloramine) are toxic to fish, so it's critical to prepare the water for their arrival. To do this, you'll need the following, all available at aquarium supply stores:

• Water conditioner, which removes the harmful chemicals

• A biological aquarium supplement, which is a colony of "friendly" nitrifying bacteria that convert ammonia, or fish waste, into chemicals that the pond's plants can use

• A pH level testing kit, to make sure the acidity and alkalinity levels are safe for the fish

• Some pH "buffers" (if necessary), which can raise or lower the pond's pH levels

Add the conditioner to the water first, using the instructed amount per gallon (or liter) of water. Then add half of the instructed amount of the biological supplement. Next, wait at least a month. This time allows the conditioners, the bacteria, and the plants to work together and stabilize the environment. Once a month or so has passed, test the water's pH levels, following the kit's instructions. When everything checks out, add the rest of the biological supplement, then it's time to move in the new tenants.

Add the fish. You can buy goldfish at most aquarium and pet stores. Pick up their food while you're there. The store will put your fish in a plastic bag for transport. (If the trip from the store to your home will take more than half an hour, leave some oxygen in the bag for safety.) When you get to your home, submerge the bag in the pond, open it, and let the fish swim out into their new home.

Note: It's critical that you not overstock your pond. Too many fish create a waste level that will overwhelm the pond's ecological balance and result in dead fish. A rough gauge is 1 inch (2.5 centimeters) of fish for every 10 gallons (45 liters) of water. Use the fish's adult length in the equation (ask the seller). To be extra safe, buy about half of this number. You can add more later.

Maintain the pond

A well-maintained pond is a healthy pond. Here are ways to keep it, and its residents, in tip-top shape:

Tend the water. A natural, non-filtering pond will never be crystal clear. However, the water might become a little too soupy for your taste. To alleviate this problem, skim debris off the surface regularly so it doesn't sink to the bottom, and change at least 10 percent of the water every 2 weeks.

To do this, fill up a large container (a clean garbage can works well) with tap water, then condition the water to remove the chlorine and chloramine. Wait the recommended amount of time for the conditioner to do its work, then use a large, measurable bucket to scoop out old water from the pond before adding conditioned water from the container.

You'll also notice muck collecting on the pond's bottom. This sludge is actually the helpful nitrifying bacteria, but you can scoop some of it out if it looks out of hand (it will build back up quickly). Being careful not to rip the liner, use a shovel or spade and scoop out about half the sludge.

It's a good idea to check the water's chemistry at least once a month. Check the pH levels with the kit, and also the ammonia levels (with an ammonia testing kit). If the levels are high, the fish could be in danger. You'll have to reduce their population, and change some of the water to get the chemistry back to normal.

Tend the fish. The fish won't need as much food as indoor goldfish because of all the bugs and plants they'll be munching on. Ask the seller how much food is recommended if it's not printed on the label.

If you live in a cold climate, the fishes' metabolism will slow down in the wintertime (fish can survive under ice as long as the pond is at least 2 feet, or 61 centimeters, deep). In these temperatures, they'll usually need to be fed about once every 6 weeks. You'll need to break the ice to do this.

Finally, keep the fish population at a sustainable level. When goldfish breed they lay up to 500 eggs. Lucky for you, they also eat these eggs, and only a few of the babies typically survive. Still, as mentioned before, you may have to cull some of the newcomers to keep the water chemistry safe.

Tend the plants. Keep an eye on your submergent plants, which can have a hard time since fish sometimes like to nibble away the leaves. If temperatures reach freezing in the winter, certain plants will need to be taken indoors (you can usually keep them in a water-filled bucket), while you can prune others down to the stems and leave them on the pond's floor, then bring them up to the tiers in the spring.

Protect the pond. If you have a dog or cat, or if your area is prone to wild critters like raccoons or opossums, consider building a protective fence around the pond. Wild animals can develop a taste for your fish, while curious pets can sometimes tear the lining with their claws.

One of the great things about a pond is the natural life it attracts. You'll soon have frogs, birds, snails, dragonflies, and more moving in--all of which will add to and enrich your lovely little habitat.

-end-