May/June 2013
Damon Roberts
Nothing excites a pond lover quite like clear, sparkling water. Regardless of the size of an architectural water body, if the water is murky or cloudy it makes for a poor impression. In contrast, clear water tends to be more enjoyable. However, clarity is only one variable that makes up the general quality of your water. While murky water does not necessarily mean poor water quality, it may be a precursor to quality problems.
Balancing Act
Water quality is a balancing act involving a number of important factors. For live systems, the balance between beneficial and harmful bacteria is one factor. The right amount of aquatic plant life is another. Taking nature into consideration is also paramount; even a heavy rainfall can shift the balance of the water.
Maintaining your water quality can seem a daunting task. But it doesn’t have to be; with these three critical keys, you can ensure your water will always be in great health.
Circulation and filtration make up one of the most effective mechanisms in your arsenal. Together, they keep water from stagnating and remove unwanted particles from the water body.
Circulation - When a water body is not circulated, stratification and anoxic conditions can result. As the oxygen levels are depleted, anaerobic bacteria processes replace aerobic processes. The water becomes murky and begins to produce an undesirable smell. The smell is a byproduct of anaerobic processes. This condition can be avoided by keeping the water moving.
Filtration - There are many types of filters available at various price points, two of the most common being sand filters and biofilters.Another good filter application for architectural water bodies is a Horizontal Sub-Surface Flow (HSSF) wetland. This is a constructed wetland where water is passed through a course gravel filter bed that’s planted with wetland plants and grasses. The gravel filters out particulates and also provides a large surface area for beneficial bacteria to grow, providing biofiltration. In addition to removing particulates, the wetland plants also remove nitrogen and phosphorus. By removing nitrogen and phosphorus, the available food source for algae is reduced.
Another important aspect of circulation and filtration is skimming the surface of the water with pond skimmers. Skimming provides a mechanism for removing floating debris, oils and algae. By removing this debris, you can reduce the work- load of the microorganisms that would otherwise have to break down these materials once they sank to the bottom of the water body.
2. AerationAeration assists in maintaining the proper level of dissolved oxygen (DO) and oxidation reduction potential (ORP) to reduce and break down excess organics. Aeration can be accomplished in several ways. Two of the most common ways include an aeration unit (i.e., a pump or blower) that can be used to introduce a column of micro bubbles to the water body; and a cascading waterfall, which introduces air as the water bounces around the rocks and falls into the pond. These mechanisms provide the added benefit of additional water circulation, particularly with an air column. With an air column, a vertical circulation cell is created that helps break up the stratification layers that can occur, especially with deep water bodies.
The introduction of an oxidizer into the airflow will also help ensure water quality. Ozone is a powerful oxidizer that kills the organics that adversely affect the water balance. It can control algae growth and help prevent algae blooms from forming. Ozone also breaks down into oxygen, which further increases the oxygen levels. Applying ozone is safe for aquatic life, but it must be applied in proper doses.
3. Water Management
The final key to water quality is the management of the water as it enters and leaves the water body. Most water leaves the system by evaporation. Therefore, in most architectural water bodies, the biggest long-term factor affecting water quality is the buildup of precipitates of salts and other elements left behind when the water evaporates. Some of these elements can be removed through filtration, but in severe situations the only way to remove them is to replace a volume of water. A regular schedule of replacing the water is the best method for maintaining the level of these elements. This can be accomplished by providing an overflow stream that dumps to a storm drain. If the water body is large enough, overflow could be used as a source for irrigation, as opposed to allowing the water to go to the storm drain.
Precipitation and Runoff
Two other important factors to keep in mind when designing water features are precipitation and runoff. Precipitation can introduce additional nitrogen when accompanied by a thunderstorm, and this nitrogen is the perfect booster for algae growth. Runoff can introduce nitrogen and phosphorus from fertilizers used on adjacent landscapes. It can also wash in organic material and dirt particles, which have a tendency to alter the balance of the water. By utilizing the HSSF wetland filtration system, pond owners can manage the additional nitrogen and phosphorus invited by these types of situations, limiting their impact on the overall system.
Final Thoughts
By designing, engineering and applying these keys correctly, you can can unlock the ability to create and maintain a high level of water quality in any size or type of architectural water body. Each of these systems can be scaled to match the appropriate environment and application. While putting these systems in place can incur some additional upfront costs, that money can be recovered in operational and maintenance costs during the years to come.
Planning, designing and engineering with these three critical keys in mind right from the start will ensure that you have a pleasing water feature that will provide value to both owner and visitors. If you are planning a new pond, lake or stream and would like to discuss these critical keys in more depth, please give us a call or send an email.
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