A backyard pond can provide a home for aquatic plants and fish, water for wildlife, glassy reflections, the gentle sound of trickling water and a tranquil setting in your landscape. A liner and sand are the only essential materials for building a small backyard pond, but you can also create hardscape edging with stones, pavers and other building materials. Pumps, filters and plants keep the water fresh by removing or recycling waste, adding oxygen and providing shade.
A waterproof liner prevents the pond's water from soaking into the soil. Flexible liners, such as those made of polyvinyl chloride, butyl rubber or ethylene propylene diene monomer, can be cut to fit the contours of the size and shape of any small pond. Depending on its thickness and usage, PVC liner can last from seven to 50 years; however, its life-span is greatly reduced by direct sunlight and some PVC liners are not safe for fish - check for a fish-friendly label. Butyl rubber is not recommended for ponds where wildlife drink but lasts 20 years or more, is more flexible than PVC and is not vulnerable to sun damage. EPDM liners are more expensive but are durable, long-lasting, flexible and last at least 20 years. Other durable options include rigid pond liners made of fibreglass and semi-rigid, plastic liners, available in a variety of shapes and sizes. Fiberglass molds last more than 50 years, but plastic molds aren't as durable. Concrete is sometimes used instead to contain the water, but it is more difficult to install, requires leaching before adding fish or plants and is prone to crumbling.
Pumps and Filters
Fish ponds require pumps to supply oxygen and filters to clean the water. Submersible pumps create little noise or disturbance, and while smaller than surface pumps, are fine for small ponds. Water cooled pumps are preferable to oil cooled, which can leave a slick on pond surfaces if they leak. Pumps with solar panels don't require a power supply but stop operating when light levels are low. If the pond waterfall, choose a pump that is the right size to send the water up to the top of the waterfall. This may still be a submerged pump. Fish ponds may also need mechanical filters or a filter attached to the pump to remove debris from the water, and biological filters, that use bacteria to break down toxic chemicals.
Constructing and edging ponds requires the use of sand and other building materials. A 2-inch layer of sand between the soil and the pond liner protects it from sharp stones in the ground. Sand can also be used to bed in edging materials such as stones or bricks, or pavers made of slate, granite, or sandstone, though fixing these with mortar gives better stability. Sprinkling sand in the shallows provides a firm footing for wildlife.
Pond plants help prevent pond water becoming stagnant and offensive, and protect the pond liner. Submerged plants use sunlight and nutrients in the water to produce oxygen, which keeps water fresh. Floating plants reduce the growth of algae by shading it out. Algae has some benefit because it produces oxygen and provides food for aquatic creatures, but it can grow out of control. Marginal plants grow in the shallow, muddy pond edges, protecting the liner from the damaging effects of sunlight and creating a visual link between the pond and the garden. Pond plants should cover about 50 percent of the water surface.
- University of California Marin Master Gardeners: Ponds -- When it Comes to Building a Backyard Water Feature, Start with a Good Plan
- Oregon State University Extension Service: Create a Garden Pond for Wildlife
- University of Maryland Cooperative Extension: Aquatic Gardening -- Construction and Maintenance
- University of Rhode Island Landscape Horticulture Program: Water Gardens
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