Creating a Water Garden

Location
  A water garden should be sited where it will be enjoyed the most.  Sun exposure should be considered if water lilies are wanted, as they need 5-6 hours of direct sun in order to bloom their best.  Places where runoff may enter the pond should be avoided because they may carry lawn pesticides and fertilizer.  Any place where nothing else will grow is a prime candidate.

 Installation
  There are two main types of liners for water gardens, rigid plastic and flexible rubber.  Rigid types are easy to install, but are typically small, and may require re-lifting every few years as the edges tend to settle.  They simply require an area to be excavated to their shape.  Add sand to the bottom only if it cannot be smoothed out due to rocks or gravel.  Make sure the edges are level and the substrate of the hole is packed tight before filling with water.  Stones or groundcover may be used to disguise the edges.

  Flexible liner usually consists of 45 mil rubber and allows the builder to be more creative.  Future additions are also possible with flexible liner.  First, excavate the hole down to at least 18”, if fish and water lilies are to survive the winter.  Incorporate shallow ledges 8-10” deep for marginal plants if desired.  Next, make sure the edges are level and remove stones or sharp objects and smooth the bottom.  It is a good idea to apply a shallow layer of mortar along the edges to prevent settling. Apply a 2-3” layer of sand on the bottom and ledges to prevent punctures.  Pond underlayment is also an option and is recommended.  After laying out the rubber liner, start filling it with water, pulling out the wrinkles as it fills.  Place stones around the edges to help hold it in place.  Water garden edging is a product that secures and hides the liner, avoiding the need for stones at all.  Samples are available for observation.  Finally, apply gravel and stones on the bottom to disguise the liner, if desired.  Avoid using limestone gravel as it raises pH.

  Concrete ponds typically crack in our area if not drained in the winter.  They also leach lime in the water, raising the pH, and are not recommended as water gardens for these reasons.

 Circulation and Filtration
  As a general rule, a pond needs a pump that circulates ½ of the total pond volume every hour.  This rule applies to ponds with a fish stock rate of 1” of goldfish or ½” of koi per square foot.  Any more fish will require more circulation and filtration.  Water gardens that are strictly plants with only a few fish may need no pump or filter at all.

  Filtration is also highly dependent on the fish that is stocked in your pond.  Koi ponds and high stock rates require larger and more sophisticated filter systems.  Some ponds with light to moderate stock rates can simply be filtered with a sponge-type filter pad, which may need regular cleaning to prevent clogging of the pump. 

  Many newly installed ponds lack surface area in which beneficial bacteria can colonize, especially pre-formed liners.  Biological filtration is a technique that involves the use of surface area for beneficial bacteria colonization to rid the pond of excess nutrients.  Biological filters usually consist of large canisters filled with lava rock, sponge, or any other media that supports bacterial growth.  Some models even feature a planting area on top for water plants to further assist in filtering.  Adding a layer of sand or gravel to the bottom of the pond can also help in biological filtration.