Designing a Pond or Water Garden
In ancient times, Egyptians along the Nile River found their paradise in the tranquility and beauty of water gardening. Centuries later, the sight and sounds of water are still cherished by gardeners, making water gardening one of the fastest growing areas in landscape design. Relatively inexpensive water-gardening hardware is making it easier for the average homeowner to incorporate a water feature into the landscape.
Before you can decide what water gardening equipment to recommend, you must first assess the your needs. Do you want a water garden primarily for its visual appeal or only for the sound of water? Are you looking for a fountain and some greenery, or seeking a pond that incorporates plants and fish? The answers can affect the type of equipment used.
Basic equipment includes liners and underlays, and filtration and aeration devices. These hardware essentials form the basic structures, which are then filled in with plants, pavers, fish and other landscaping.
One-Liners
Liners are a crucial material because they contain the water and keep it from dissipating into the soil. You can use a flexible liner, which is a flat sheet of heavy-duty plastic material, or preformed pond, which is a ridged formed liner.
You should use a flexible pond liner if you want a uniquely shaped pond. An abundance of flexible liner types are available. Polyvinyl chloride (PVC), the least expensive material, and is available in a variety of sizes. Its thickness ranges from 20 mil to 30 mil. Most suppliers warranty PVC liners for up to five years, but the material is susceptible to ultraviolet degradation. The life expectancy of PVC liners is five to seven years.
Nursery professionals and customers prefer the pond liner material ethylene propylene-diene material (EPDM). While it is approximately twice the cost of PVC material, it is often worth it. Generally 45 mil thick and available in a variety of sizes, EPDM has at least a 10-year warranty and a life expectancy of 50 years. EPDM is similar to material that is used for rolled roofing, which is employed for waterproofing flat roofs. Unlike rolled roofing material, though, EPDM is safe for fish and plants.
Digging and Forming
Some soils are easier to work with than others. In very sandy soils, side walls of more than a 45′ angle tend to collapse. Loam soils permit side walls of up to a 75′ angle, and heavy clay soils hold at a 90′ angle.
Water-Garden Installation Steps
When you dig a hole for the pond, make sure the water garden is at least 18 inches deep in order for fish and plants such as water lilies to thrive. Leave some areas only 8 inches to 10 inches deep so they can be used as planting shelves for marginal plants, which prefer shallow water. Make the sides as steep as possible to give the illusion of depth. Steep sides provide a bonus: Animals, such as raccoons, are discouraged from entering the pond. You can also leave a small, shallow area for birds.
Before installing the liner, you need to figure out the correct length of material needed. To do this, add the maximum length of the pond to twice the maximum depth. You need to perform this entire calculation, because your liner must go across the length of the pond and up and down the sides. Then add to the sum another 2 feet. This extra material will help prevent the liner edges from falling back into the pond. For example, if the hole is 4 feet long and 2.5 feet deep, the formula is as follows: 4 + (2.5 x 2) + 2 = 11 feet long. To figure out the liner width, perform the same calculation, substituting width as the variable.
After cutting the liner to the desired shape and size, you need to take several preliminary measures before installation. First make sure the bottom of the hole is level. Then apply an underlay material, which will protect the liner. The best material to use is a pool base, a mixture of vermiculite and cement used to protect vinyl lined swimming pools. Carpeting or newspaper are other protective underlay materials. Don’t use a sand base, though, because the natural ground water that moves through the soil can dislodge it.
Place the liner into the pond and smooth it as much as possible. Once the liner is installed, you can immediately fill the pond with water. Next, trim the excess liner and place your coping material (decorative material, such as rocks or plants like a weeping cotoneaster) around the edge of the new pond.
You may wish to secure the coping on the top of the pond. Prepare a mortar mix, place mortar material 2-3″ thick in an 8″-12″ band around the edge. Set coping stones into the mortar. If you plan to stand on the coping, it would be advisable to put wire into the mortar to provide extra strength.
Preformed, ridged liners
Installing a preformed pond is more labor-intensive and time-consuming. Yet preformed ponds, which essentially are formed liners, appeal to first-time users because they can easily imagine what the finished pond will look like.
These ponds are available in a number of materials. High-density polyethylene is one of the most durable and the most widely available. Polyethylene ponds have a five- to 10-year warranty, and generally last 15 to 20 years. Preformed ponds are also available in fiberglass, often in do-it yourself kits. Fiberglass ponds are expensive, but they are an excellent choice because they last a lifetime.
Before installing the pond, dig out the area in the shape of the formed liner. It is very important that the bottom of the hole is level. Make sure that you anticipate and adjust the soil depth needed for any formed shelf areas. For example, if the maximum depth of the pond is 20 inches, and there’s a shelf area in the center that is 8 to 10 inches deep, you need to make sure that the soil in the center of the dug area is packed to that depth. This ensures the shelf area is well-supported. Remember, if a pond is not properly supported and level throughout, the formed liner will warp and crack. In addition, water will float under the liner during times of heavy ground water, and you will have to reset the entire liner.
Insert the pond into the hole and make sure the surface is level. Pour 2 inches to 4 inches of water into the pond and place 2 inches to 4 inches of excavated soil between the pond wall and the ground wall. Make sure the soil is well-packed, so the water pressure will not push the side walls out. Continue adding water and backfill in this manner until the pond is full.
When purchasing a pond, take into account that regardless of the material used, a finished preformed pond will appear about 35 percent smaller than it is when viewed out of the ground. An alternative to a liner is a concrete pond, which is requested by those who want a permanent pond.
Corporate campuses are more likely to have concrete ponds than residences. Concrete is the most expensive material to use and install. A landscape architect creates it by building a form (usually made of plywood) in which concrete is poured. This kind of pond requires more maintenance than ponds with liners. It also needs to be sealed to prevent leaching of lime from the concrete into the pond water. Lime can adversely affect the quality of water and, subsequently, pose a threat to plants and fish. Clay is the old-fashioned answer. Clay should be slightly bluish in nature, clean and free from rocks and debris. Compaction is the secret. Pound moist clay into a 8″-12″ layer with your feet. Most of the old English lakes were lined this way. They work well after hundreds of years.
Water Management
After the pond is installed, hardware purchasing is not yet done. Filtration is essential to remove debris. To select the appropriate filter for the pond, determine first the number of gallons it holds. To do this, multiply the length by the width by the average depth. Then multiply the result by 6 (the number of Imp. gallons in a cubic foot). For example, if the pond is 6 feet long, 4 feet wide and has an average depth of 3 feet, the formula would be 6 x 4 x 3 x 6 = 432 gallons of water.
Be prepared for evaporation. Your pool will loose up to 10% by total volume on warm, windy days. This may be best appreciated as 1″-2″ of water. An automatic type of water feed will save much difficulty. A toilet type float valve will do. To effectively remove debris, make sure pond water is circulated once every two hours. Pumps are rated by the number of gallons per hour they process. So if the pond contains 432 gallons of water, you need a filter that can process a minimum of 216 gallons per hour.
Use a biological filter only if the pond is overpopulated with fish. The excess ammonia compounds in fish waste are toxic to organisms. The biological filter contains bacteria that converts these toxic ammonia compounds into nitrites. Another bacteria then converts the nitrites into nitrates, which are released into the water and can readily be used by aquatic plants. If you are using a biological filter, the entire pond should be filtered once every four hours.
Just as vital to water gardens as filtration is aeration, which helps re-oxygenate water by circulating it. This means a pump that pushes water through a fountain spray, piece of statuary or over a waterfall is necessary. As with debris removal, you need to circulate pond water once every two hours for effective aeration.
A number of fountain heads for aeration are available on the market today. Little Giant Pump Co., Oklahoma City, for example, offers almost 20 spray-head varieties. To find out which fountain head is appropriate for the number of gallons in your pond, consult the manufacturer’s literature.
When you construct artificial streams or waterfalls, you need to assess how much water is necessary to create the effect you are trying to achieve. If you want a veil effect (thin sheet of water) for instance, you need 240 gallons of water flowing per hour for each foot of width. To create a rush of water, you need at least 80 gallons of flowing water per hour per 1 inch of width.
Pumps and filters
One properly sized pump is capable of running all the necessary pond components. Most manufacturers offer kits that contain a pump, filter and fountain spray.
To select the correct pump size, you need to consider several factors: the flow of water necessary for the fountain head or waterfall, the filtering requirements of your pond, and the maximum height that your pump must lift the water.
Some pump manufacturers rate their pumps at zero feet of head, or lift. This means that they rate the pumps as to how high they can pump the water starting at water level. Others, like the Little Giant Pump Co., rate their pumps at one foot of head, meaning the starting point is 1 foot above water level. Consult the pump manufacturer’s literature to assess the flow of water needed to reach the desirable height.
It is very important that the pump you select is Underwriter’s Laboratory (UL) listed for the application. Other features to consider when selecting a pump are cord length, color and required maintenance. For most pond applications, a 15-foot long power cord is adequate; a shorter cord makes it difficult to properly place the pump in the pond. As for color, a black pump blends in the best with most pond liners. A pump of a different color is highly visible in a water garden.
Maintenance
Maintenance requirements depend on the type of pump chosen. Submersible magnetic drive pumps are generally very energy efficient. In addition, these kinds of pumps require significant maintenance: You must frequently remove them from the pond to be disassembled and serviced. Epoxy encapsulated pumps are also energy efficient and require little maintenance. They are very compact and easy to hide in the pond. With a generally higher head than the submersible magnetic drive pumps, they are a good choice for water gardens.
The best choice, however, are oil filled pumps. They are filled with a nontoxic dielectric mineral-type oil. For all practical purposes, these pumps are maintenance-free. These pumps have the highest water flow and the longest life.
Lighting
Beyond basic pond hardware, enhancement features are also important. Lighting in and around the water garden, for example, can increase its aesthetic appeal. In addition, a lighted pond can be enjoyed 24 hours a day. Submersible low-voltage lights and step-down transformers (devices that reduce the electrical power) are available separately or in kits. Lighting kits also include colored lenses and mounting brackets for the lights. Lights generally have 20-foot-long cords. Like pumps, the lighting that you select should be UL listed for the application.
Water gardening can be rewarding for customers, but also somewhat daunting. It’s up to landscapers and other nursery professionals to walk you through the process and answer questions along the way.
Adapted from American Nurseryman May 1, 1996 and an article written by Tom King president of B.A. Heskett Inc. of Olmsted Falls OH.
Pictures scanned from water garden brochure – LITTLE GIANT PUMP CO.
