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Creating a Healthy Ecosystem

Joe Olenik//March 17, 2014//

Creating a Healthy Ecosystem

Joe Olenik //March 17, 2014//

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As pond keeping and water gardening increase in popularity, more and more owners are turning to natural ecosystems as the method of choice for managing their creations.

A properly designed, balanced aquatic ecosystem will provide its owner with years of trouble-free enjoyment, and will be much more stable and aesthetically pleasing, than one that relies on chemical additives and artificial means. It is essential for retailers to understand the dynamics of a balanced aquatic ecosystem in order to provide sound advice and ensure their customers’ success and long-term involvement in the hobby.  The following principles are natural, relatively easy to implement, cost-effective and sustainable. 

The most important aspect of managing a pond or water garden, and the one that gives novices the most trouble, is dealing with nutrients from fish waste.  Even minor accumulation of nitrate and phosphate in a pond can produce unsightly and stubborn algae blooms.

Most algae problems can be traced to an imbalance in the ecosystem.  Conventional methods of algae control have typically focused on the use of chemical algaecides, preventives like barley straw or barley extracts, or filtration media designed for nutrient removal.  While sometimes effective, all of these products or techniques can be expensive and require frequent replacement.  Proper planning in terms of pond size and depth, filtration, stocking, and the use of plants to absorb nutrients, will alleviate the need for artificial methods.

Breaking It Down

Size does matter.  A larger body of water can support more fish, absorb more nutrients, and is more stable than a smaller one.  Bigger is better when it comes to outdoor ponds, so retailers should encourage hobbyists to create as large a feature as their available space and budget can accommodate.

Pond depth is also important.   This is especially important when a large surface area is not possible due to limited space.  A minimum depth of 36 inches is essential, especially if fish are to be kept over winter in climates where the pond will freeze over.

Filtration is even more important, as it determines how much waste can be processed.  Most manufacturers rate their pond filters in terms of gallons of pond water, but make no mention of the number and size of fish they are capable of supporting.  Here again, bigger is better.  Always recommend a filtration system rated at 50 percent to 100 percent higher capacity than the size pond it will be installed on.

Circulation and aeration go hand in hand with filtration.  Supplemental pumps to move water around the pond, fountains, waterfalls, streams or cascades all help to increase the oxygen content in the water, which helps break down waste and process nutrients.  Make sure you recommend these add-ons when getting hobbyists started with their first pond or when helping to solve algae problems.

Stocking density refers to the number and size of fish in the pond relative to gallonage and filtration capacity.  Keeping this low is crucial to maintaining a healthy balance.  It’s important to remind customers that those cute little koi or goldfish will be lunkers in just a season or two.  An overcrowded pond will quickly result in algae problems and maintenance headaches.

It’s fun to feed fish, especially koi, as they become very tame and will eat out of your hand.  But remember, what goes in must come out, and what comes out is pollution and food for algae blooms.  Excessive feeding will overwhelm the filter and quickly lead to nitrate and phosphate buildup.

Most pond fish forage on natural foods available in the pond, so feeding should be done sparingly and limited to what the fish can consume in 2 minutes or less, once a day or even every other day.  It’s helpful to actually demonstrate this in a store pond or aquarium containing pond fish.

Finally, and most importantly, a true aquatic ecosystem is dependent on the use of plants to remove nutrients and maintain good water quality.  Floating plants such as Water Hyacinth and Water Lettuce provide shade and grow rapidly, removing nutrients in the process.

Underwater plants, also known as oxygenators, such as Elodea sp., Hornwort (Ceratophyllum demmersum) and many others have the same effect, however, are best suited for ponds housing goldfish and smaller koi, as larger koi will quickly devour them.

Emergent or marginal plants can be potted and placed on ledges in the pond, and will provide additional nutrient removal.  A heavily planted pond with low fish population will stay crystal clear and require minimal cleaning.

Sometimes referred to as wetland filters, bogs are gaining in popularity among pond owners.  A shallow basin is dug adjacent to the main pond and lined with pond liner material.  Water is pumped from the main pond through a grid of PVC pipe which is covered with pea gravel.  As water wells up, nutrients and pollutants are absorbed by emergent plants planted in the pea gravel. Irises, cat tails, rushes, taros, sweetflag and a variety of other plants that like their feet wet can be planted in the bog, creating a beautiful garden that also becomes an inviting habitat for visiting birds, frogs and other wildlife.  Bogs require little maintenance and provide both beauty and function to any aquatic ecosystem.

By offering your customers the products, equipment and livestock they need, and providing the knowledge and expertise to make them successful, aquatic retailers can develop long-term loyalty and compete effectively with nurseries and home improvement centers in the water gardening marketplace.