Introduction
Nothing transforms a yard like a water garden.  The sounds of water are soothing and relaxing while the vision of water is an oasis of cool tranquility.  The serene lushness of exotic plants mingled with the graceful movements of colorful pond fish have provided a sense of calm and peacefulness to countless numbers throughout history.  Today, many homeowners are transforming their yards with beautiful, low-maintenance water features. 

Types
Water Garden - A water garden usually contains a variety of aquatic plants and often has goldfish.  Water gardens in Minnesota need at least 12”-16” of water below the freeze zone for goldfish to survive, or the pond will need to be drained each fall and the plants and fish overwintered indoors.

Koi Pond - A koi pond is different.  Koi limit the amount of plant life available for use because they eat some aquatic plants.  They also grow quite large regardless of the size of the pond.  Koi ponds should be at least 1000 gallons in volume and more than 5’ deep in Minnesota if koi will be overwintered.  Alternatively, if overwintered indoors, koi can be kept in shallower ponds of 3’during the summer.

Site
Location - The first consideration is where the pond will be situated.  The best site allows it to be seen and heard from the home and blended with the natural landscape.  Position the pond away from trees to keep leaves and other debris from dropping into the water.  Decomposing leaves generate gases that may stress or kill fish, and they also release nutrients into the water increasing algal growth.  Situate the pond to avoid the flow of run-off that may carry fertilizers, chemicals, and debris into the pond.

Light - Shade is adequate for ponds containing only fish, but most aquatic plants require at least 6 hours of daily sunlight to bloom.  To ensure sufficient light before construction begins, lay a rope or garden hose out in the size and shape of the pond and observe the site several times throughout the day when the sun is shining.  Allow for the seasonal variation of the sun’s path.

Preparation
Size - The biggest mistake most home gardeners make is constructing a pond that is too small.  Larger ponds are more stable and easier to maintain; smaller ponds limit the plants and fish that can be used. 

Construction - Pond kits that are complete and ready-to-assemble are now widely available.  Always check with all utility companies concerning underground lines before digging.  Dig the hole for the pond keeping the top edge of the pond level—an unlevel pond will overflow at one end while the other end stands half empty.  As construction progresses, the levelness of the pond’s top edge should be continually rechecked. 

Filtration
Mechanical filtration is needed to handle debris while biological filtration is needed to handle nutrients.  Position any external pond filters/skimmers at the proper level beside the pond.  Consult your pond kit instructions for more information on installing the filtration system.

Mechanical - Mechanical filters remove solids from the pond by trapping the debris in a mat, brush, or sponge.  They are effective but may require weekly cleaning.

Biological - Biological filters reduce built-up waste producing healthy water conditions for fish.  Nitrate, the end-product of the biological breakdown process, is used by both aquatic plants and algae so bio-filters are best used with a healthy proportion of aquatic plants. Bacteria/enzyme products also breakdown organic compounds and improve the water quality of the pond.   Barley straw or barley straw extract added to the pond helps reduce string algae buildup.

Pumps and Plumbing
Recirculation of the water in a closed system keeps water fresh, allows gases to escape, and adds oxygen to the water which is critical for supporting bacteria and fish.  The company where the pond kit was purchased can provide assistance in obtaining the proper submersible pump with the right flow rate for the pond’s size.

PVC Liner and Underlayment
Good PVC liners are made of fish-safe, 45 mil black rubber and are UV resistant, very flexible, and easy to work with even in cold temperatures. 

Installation - After the required shape and depth of the pond has been dug, line the pond with an underlayment to protect your PVC liner from roots, stones, or other sharp objects.  Once the underlayment is in place, position the PVC liner evenly in the center of the pond and begin to fill it with water.  As the pond fills, smooth the liner to minimize folds and wrinkles.  Remember when plants are added they will help hide wrinkles.  Refer to the detailed instructions included with the pond kit for more information about installing the underlayment and PVC liner.

Additional Information
For more information, refer to the University of Minnesota Extension Service Consumer Horticulture webpage at http://www.extension.umn.edu/ConsumerHort/

Sources
Water garden/pond kits may be purchased at local garden centers and nurseries or through mail order sources.

Thank you to the individuals and businesses who have contributed to the Water Garden by donating plant materials, time, or funding.  This is informational only and does not represent an endorsement by the University of Minnesota.

Rocks and Gravel
Rocks and gravel protect the liner from harmful ultraviolet rays while helping to prevent hydrostatic bubbling.  And, when used to cover the bottom and sides of the liner, they provide the perfect substrate for bacteria to colonize thereby increasing water clarity.  Use only smooth rocks and gravel.

Algal Growth and Control
Algae in ponds is caused by several factors occurring simultaneously including sunlight, under planting of aquatic plants, overfeeding of fish, lack of filtration, water run-off, and phosphates in the water.  Covering at least 60% of the pond’s surface with aquatic plants is the best method of controlling algal growth.  The plants shade and cool the pond and compete with algae for nutrients. 

Aquatic Plants
A balanced pond must contain enough plants to consume the waste produced by the fish and to shade at least 60% of the pond’s surface. 

Types - There are four types of aquatic plants.   A mix of types keeps a system self-sustaining.  Deep Water plants include hardy water lilies, lotus, spatterdock, and tropical water lilies.  Floating plants include azollo, duckweed, water-meal, water ferns, water hyacinth, water lettuce, and water poppy.  Submerged plants are oxygenating and are commonly used at rates of 1-2 bunches per square yard.  They include anacharis, cabomba, dwarf sagittaria, and vallisneria.  Anacharis is an important plant because it uses up nutrients that would otherwise feed algae.  If stocking your pond with Koi, you must protect the anacharis from being eaten.  Bog plants include arrowhead, bog lily, bull rush, canna, cattails, chameleon plant, Chinese water chestnut, golden club, creeping primrose, dwarf bamboo, dwarf sweet flag, Egyptian paper reed, floating heart, hairgrass, horsetail, lizards tail, marsh marigold, and papyrus.

Stocking - In a new pond, plants should be added several weeks before introducing the fish.  Most aquatic plants are aggressive and should be planted in containers.  The recommended planting medium is a heavy garden soil with high clay content that is free of pesticides, compost, and manure.  Do not use commercial potting mixes unless specifically designed for aquatic plants.   Containers with drainage holes should be lined with landscape fabric, untreated burlap, or several layers of newspaper to contain the soil.  Place the plant in the container and fill with the planting medium leaving the top 2” for gravel.  Gravel prevents the soil from floating out into the pond.  Once the plant is potted, position it on the pond shelf so water covers the top of the pot.  The water depth depends on the plant species – a minimum water depth of 14 inches is required for most aquatic plants.

Pond Fish
The combination of fish and aquatic plants balances a pond, but don’t overcrowd your pond with fish.  One 3”-5” fish per 10 gallons of water is plenty considering the fish may double in size by the end of the summer. 

Types - Aquarium, tropical and bait fish are not suitable for ponds.  Goldfish and Koi work best.

Goldfish are very hardy.  Popular varieties are Shubunkin, Calicoes, Orandas, and Fantails such as Chinese Moors and Comets.  Golden Orfe do not adapt well to hot Minnesota summers.  Koi are very popular in warmer climates.  They can grow 2’-3’ long and can become feed aggressively on container plants when overstocked.

Stocking - Once the pond is filled, wait 24-48 hours before stocking with fish to allow the chlorine to evaporate.  The ideal pH for fish is 7.0-8.5.  Test the water before adding fish.  Help the fish acclimate to the water temperature of the pond before release by floating them in a plastic bag on the surface of the water for 15-20 minutes.  Place a wet newspaper over the bag to keep out the sun’s heat.  Most ponds will provide adequate food so feeding is not necessary; however, most gardeners enjoy feeding their fish.  Keep the feeding to a minimum to avoid overgrown fish and cloudy water from excess nutrients.