Oxygen is essential for life to exist, above and below the water. To keep a pond and its inhabitants healthy, it is important to have the right amount circulating in the water. Nature usually supplies ample amounts of aeration through wind, rain, and other means. However, in garden ponds additional nutrients such as runoff, grass clippings, and leaves from neighboring trees can leave a pond needing more oxygen. The lack of oxygen can bring on detrimental effects so it’s important to stay vigilant, especially in warmer temperatures.
Here are some of the most common warning signs for insufficient oxygen:
Fish gasping at the surface, usually in the early morning
Foul odors emitting from the pond
Excessive amounts of string algae
If you do not see any of these symptoms, you may be in luck. However, it’s still important to make sure your pond is properly oxygenated to avoid future problems.
Benefits of Aeration
Aeration is the process by which air is mixed with a liquid. Ok – but why is this important for my pond? Good question.
The most important benefit of aeration is destratification. When pond water is not adequately circulated it can cause stratification, the layering of a body of water based on differentiating temperatures. In the summer the top of the pond will be the warmest and the bottom the coldest. A stratified pond does not allow its inhabitants to swim freely because certain areas contain more oxygen and nutrients than others. Proper aeration will distribute cooler oxygenated water to warmer areas with lower amounts of dissolved oxygen. This allows inhabitants to occupy all areas of the pond.
Water quality and clarity is also improved through aeration. Pond debris and muck release noxious gases. With proper aeration, high levels of carbon dioxide are removed from the water. CO2 is only dangerous when it’s allowed to convert into carbonic acid, which brings down the pH levels of the water making it nearly toxic. Aeration also reduces phosphorus concentrations in ponds. Phosphorous supports green water and the string algae. In essence, more aeration means less algae.
Types of Aeration
There are several ways to aerate a pond. The most common way to aerate a pond is through sub-surface diffusers, but more aesthetically pleasing options are available.
An aerator is the easiest and most efficient way. Aerators use air stones to diffuse injected air, creating tiny air bubbles. The rising bubbles ensure high air volume. During the summer when oxygen levels decrease, the best place for the aerator is at the very deepest point of the pond.
Waterfalls are a popular aeration option, with the added benefit of natural beauty. Waterfalls work from the top-down, forcing freshly aerated water into the pond. Although pleasing to the eye, the waterfall’s flow rate may not provide sufficient aeration for the entire pond. Additional aeration will be beneficial, especially for ponds with a depth of over 48 inches.
Fountains, bubblers, and spitters are other options that aerate and accent your pond. Every time the water circulates through the feature, it comes in contact with the outside air. The exchange refreshes and brings more oxygenated water into your pond. These are not sufficient enough by themselves, but when used in conjunction with another source could provide the right amount. If relying solely on this method, a testing period is recommended.
Additional Tips for Proper Aeration
Aquatic plants are an essential part of having a pond. They provide shade and produce oxygen during the day. At night, those same plants use oxygen for respiration. If the call for oxygen at night exceeds what was produced the previous day, your fish can suffer. This makes the percentage of plant coverage important. No more than one half of the pond should be covered.
Proper filtration is one of several main components for a healthy pond. If pond filters are maintained regularly, they will efficiently provide water movement and remove waste.
Decaying organic matter like leaves, grass clippings, or fish waste use up oxygen. Avoid dealing with it all together by using a surface skimmer. But if the debris has already sunk to the bottom and cannot be removed by regular filtration means, a pond vacuum will do the trick.
Overall, aeration provides many benefits to a pond’s ecosystem. After incorporating some or all of the recommendations above, monitor your pond and fish frequently. If warning signs continue or new ones emerge, contact your local water treatment specialist to see if other tools are available to boost the health of your pond