Pond aeration can come in a variety of forms but regardless of how you choose to aerate a waterbody, you can be assured that the aerating process will have a beneficial effect on the water quality in a pond or lake.

Aeration can aid in solving oxygen and circulation problems in a pond, while also decreasing the likelihood of a fish kill, reducing odors, improving water clarity, and minimizing undesirable algae growth. It is essential for maintaining a healthy pond environment for fish.

In this article we'll take a deep dive into using aeration in ponds...how it works, what it actually does, and why you might want to consider installing it in your pond. We'll cover the various types of aerators you'll find on the market today as well.

Table Of Contents

• Why You Should Consider Aeration For Your Pond
• How Aeration Works
• Oxygen Transfer Happens At The Surface
• Aerations Benefits For Fish Ponds
• Healthy Ponds Are Naturally Cleaner
• Reducing Odors And Improving Clarity
• Aeration For Algae And Weed Management
• Aeration Aids In Natural Mosquito Control
• Types Of Aeration To Consider
• How To Choose The Best Aerator

A typical sub-surface pond aeration system

So why would you even want aeration in your pond? Well, it really comes down to two things. Movement or circulation, and dissolved oxygen. Both are vital to maintaining a healthy pond for fish, and one that will typically enjoy cleaner or clearer water.

Stagnation, on the other hand, is an all too common problem in many ponds. Many suffer from poor circulation, and low oxygen levels, which increase the chances of a fish kill. Both will typically make a waterbody more prone to algae blooms, foul odors, reduced water clarity, and undesirable weed growth as well.

Aeration is the best solution for both oxygen and circulation problems in a pond.

In very simple terms, the act of aerating involves the injection of air or water back into the pond water in order to create some movement. We'll talk more about the different types of aeration later on, but for now, we'll note that fountains propel water into the air (often in some decorative pattern) and those water droplets go back into the pond via gravity.

Another very common aerator used today involves a land-based pump, some airline, and a diffuser that sits at the bottom of the pond. The diffuser is the key to this system because it creates very fine bubbled air. These rise rapidly to the surface...and work, in a sense, in the opposite direction of a fountain. Be it water droplets or air bubbles, the aerator creates the necessary surface agitation to get atmospheric oxygen into the water.

A pond fountain with a vertical spray pattern

You read that right. The actual intake of oxygen into the water will always happen at the surface. For a reasonable amount of oxygen to enter the pond, the surface tension of the water must be disrupted or reduced, and this agitation can come in from a fountain spray, or diffused bubbles released from the bottom of the pond. In nature, rain droplets can help, as can the wind, which creates waves on larger ponds and lakes. All provide a better intake of oxygen into the water.

Proper Mixing Of The Pond Water Is Helpful

The other positive thing that comes from mechanical aeration is the mixing of the water throughout the pond. Stagnation can create thermocline layers or layers of different temperatures and dissolved oxygen levels as you work through the pond from top to bottom. These are typically undesirable and problematic for fish and they limit how much of the pond the fish can actually inhabit. These layers will also usually indicate better oxygen levels near the surface but very low levels at the bottom. For a healthy pond however you want good dissolved oxygen levels throughout. 

Overall, no matter what type of aeration kit you use, the health of a pond can improve by increasing oxygen levels and circulation. Through the aerating process, many people see a reduction in the growth of things like unwanted algae and other undesirable organisms. In addition, it can also help to prevent fish kills and improve the water quality of the pond.

For a pond with fish, aeration can help support the health and vitality of any species, and it may be a life safer for others during periods of stress. Here are some specific benefits that aeration can provide for fish ponds.

Aeration can protect fish in all seasons

Adequate Oxygen Is The Key To Healthy Fish

First and foremost we need to talk about oxygen levels. Fish need reasonable amounts of oxygen in the water to survive, and an optimum amount to thrive. A good level in a pond to support fish is typically between 5-9 mg/L (milligrams per liter), and a minimum of 4 mg/L is needed to support fish life.

Optimum DO levels will vary by species of fish and can also be affected by the water temperature. The main consideration though is that the DO doesn't drop too low to cause problems and harm fish. Generally, warmer water (above 78 degrees F.) will hold less dissolved oxygen than colder water, so aeration can be particularly useful for fish protection during the summer months.

For additional advice on avoiding fish kills, and how aeration may help, visit the PennState Extension website.

A pond aerator will often help improve a pond's water quality. There is a normal build-up of organic material in any pond, and over time, gases such as methane and hydrogen sulfide can accumulate at the bottom. Increasing oxygen, low in the pond, and providing some circulation will help to neutralize this off-gassing, and promote the breakdown of any organic matter that's accumulated over time.

Pond aeration can make fishing more fun! Image by Gio Spigo

Fish tend to just be healthier with good oxygen levels in the water. Because of this, we've often seen more vitality and better growth rates of all species in well-aerated ponds. Bigger fish and better fishing are a nice benefit!

Oxygen happens to be essential to the decomposition of organic matter by aerobic bacteria or microbes found naturally in ponds. This is important because as we mentioned previously, this build-up of organic material, which is much like compost you'd see used in a garden, will create and release various things as it slowly decays.

Odorous gases are one of the byproducts of this build-up. So reducing the organic load in a pond can be helpful for a pond that smells bad. Sometimes aeration alone will solve the problem, but if not, we have used beneficial microbes in combination with it to good effect. 

Algae in limited amounts can be a healthy part of an aquatic ecosystem. If it blooms out of control however, it can turn into an eyesore, or at it's worst, a toxin-laden growth that can be dangerous for people, pets, livestock and wildlife.

A healthy pond makes good habitat. Image by Tom Fisk

Aeration may be useful in keeping it under control. Over the many years of working with pond owners, most of who were fighting algae, we noticed that many experienced improvements in their pond's appearance, when using aeration all on its own. This is not to say that every pond improved, but many did.

The reason for this is not so much that aeration controlled the algae. Aeration simply provided the necessary foundation for a pond's natural aerobic bacteria to work better. In doing so it reduced the nutrients (like phosphorus and nitrogen) in the water that were feeding the algae growth...do that and algae will often regress.

Our Strategy For Algae Control - Aerate And Use Beneficial Microbes If Necessary

Our typical strategy now regarding any pond with algae, is to add an aeration system first and then monitor the pond's condition for a couple of months. If we don't see a noticeable improvement in that time frame, we may supplement beneficial microbes into the pond for a while...and often those two things, when combined, can turn many algae-riddled ponds around.

Beneficial Bacteria For Ponds

Can Aeration Help When You Have Aquatic Weeds

And what about weeds? Weeds unlike algae will usually root in the nutrient-rich muck of a pond. You can reduce this build-up with aeration and a muck-digesting type of bacteria and over time, as the pond bottom gets cleaner, the opportunistic weeds we'll be less likely to get a good footing. Aeration however will not have a direct or immediate influence on aquatic weed growth.

If you decide to treat a weed problem with some chemical application, aeration will usually help in the circulation and absorption of the treatment, and secondarily it will provide protection for fish in the pond during the die-off of the plants. Note: Any plant that is dying, will pull dissolved oxygen from the water in the process.

Mosquitos love stagnant, standing water! It makes a perfect breeding ground for these pesky disease carrying insects.

Continuous aeration keeps the water in motion which can make it difficult for mosquitoes to lay their eggs. The added oxygen also supports other aquatic organisms that feed on mosquito larvae.

Overall, pond aeration can help to create an environment that is less attractive to mosquitoes, which can help to reduce the number of mosquitoes in an area.

Because the focus of this article is covering how a pond can benefit from aeration, we'll only briefly talk about the types of systems you'll find on the market today and how we might consider using them. We'll get a lot more in-depth with aeration methods and how to choose the best one for your particular application in an upcoming article.

Kasco Marine Surface Aerator

In no particular order of preference, all of the following can provide some form of aeration to a pond.

• Surface aerators: This type of aerator floats on the surface and circulates a high volume of water, which is good for very high oxygen demand situations or shallow ponds.
• Pond Fountains: A fountain is surface-based and provides a balance between an attractive display and aeration.
• Sub-surface Pond Aeration: These aerators use a land-based pump, and weighted airline, which connects to a diffuser that sits at the bottom of the pond. These affect the entire pond and can work at depths down to 50'.
• Shallow water aeration systems: Shallow water systems are specially designed for ponds 6' deep or less.
• Solar pond aerators: These aerators use solar panels to power a motor that drives an aeration system. Two types are available...daylight operation only and full-time operation with a battery backup.
• Windmill aerators: These aerators use the wind to power a motor that drives an aeration system.

Solar aerators are gaining in popularity

It is best to consult with an aeration professional to get the right type and size of aeration system for your needs.

As a general rule though if we take the Kasco brand of surface aerators as an example, they suggest allowing for 1 HP for every acre of surface area. This would apply to their fountains as well and is mainly in regard to the aerating capability. With fountains, the height and spread of the spray pattern would also be a factor in properly sizing it to a pond or lake.

For sub-surface systems, the surface area, as well as the depth of the pond, are the main considerations. The deeper a diffuser can be placed, the more pond area it will affect. All manufacturers have recommendations on what size system will work best on the pond size and depth coverage. For example, the Kasco RA1 aerator with a 1/4 HP rocking piston pump, and a single diffuser, will cover up to a 1-acre pond if the diffuser can be placed at a depth of 12 feet or greater.

Ideally a bottom based aerator should turn the pond's water volume over about once per 24 hour period at a minimum.  A little more is fine too, but there is a point where too much, or too aggressive aeration is not helpful, and in fact could be problematic for fish during very hot weather. 

How Important Is Aeration For Ponds? - Some Final Thoughts

We view aeration as one of the most important, if not THE most important thing a pond owner can install to help with the overall health and vitality of their pond and its inhabitants. Increased oxygen levels from the top to the bottom of the pond, along with improved circulation, provide a better environment for fish, and it allows the pond's natural cleaning processes to work better too. This results in a healthier, better-looking pond that's easier to maintain, and care for. Most people find them to be far more enjoyable to be around as well!

We hope you've found this article useful. If you have questions come up, please reach out anytime and we'll be happy to help you with your pond challenges.

Other Related Articles You May Find Helpful

• How To Install Any Kind Of Pond Aerator
• What You Need To Know About Aeration In Hot Weather
• What Maintenance Is Needed For Rocking Piston Aeration Pumps?