How to Maintain a Balanced Pond Ecosystem

How to Maintain a Balanced Pond Ecosystem

Ornamental fish ponds and water gardens look great when they’re first set up. Over the next month or two many new pondkeepers get discouraged when they see the pond looking less than pristine. The truth is backyard ponds will never be as clean as a swimming pool. That is completely unnatural and quite impossible to achieve. A healthy pond will always have a little bit of algae, dead leaves, and even some bugs floating on the water. This is exactly what you’ll find in nature. And didn’t nature inspire you to set up a pond in your backyard?

Nobody wants a messy-looking pond with stringy algae, green water, and sick fish. But the fact is inexperienced pondkeepers sometimes cause this by creating an unbalanced pond ecosystem. You often hear about “maintaining a natural balance” to keep the pond looking good. But what does that actually mean? It’s not as complicated as you may think!


Understanding Balanced Pond Ecosystems

A balanced pond is one where the water is clear and free of excessive algae. The aquatic plants are thriving. The fish are vibrant and healthy. But what’s an unbalanced pond? We’ll explain that in a bit. But first, what kind of pond do you have? A fish pond or a water garden? How you manage your pond’s ecosystem depends on the kind of pond you have.


Fish-Only Ponds

A fishpond is designed to show off koi and goldfish. Typically, the primary objective here is to maintain pet fish, often with the goal of stocking the pond with a collection of goldfish or colorful koi. In such ponds, aquatic plants are either limited in number or completely absent.


Water Gardens

Water gardens cater to those who have a passion for nurturing beautiful aquatic plants. Enthusiasts in this category focus on growing plants like water lilies, irises, and various leafy or flowering bog and marsh plants. Some water gardeners may introduce a couple of goldfish to provide movement and help control mosquito populations. 

However, for most of us, the desire is to create a harmonious blend of aquatic plants and stunning fish. This typically involves incorporating a wide variety of aquatic plants along with fish species that are conducive to plant growth, such as comets, shubunkins, and fantails.


Natural vs Backyard Ponds

Novice pondkeepers often wonder why they must be concerned about water quality because natural ponds seem to take care of themselves. The fact is a backyard pond is very unnatural.  Think about it. A hole was dug in the ground and covered with a rubber liner. The pond was filled with tap water.  Maybe a waterfall was installed. After that, goldfish were added along with a few plants. 

Natural ponds are much larger, have a 1000-times less “fish-per-gallon “ratio, and often have a spring or stream feeding freshwater into it all the time. This self-sustaining ecosystem is much different than a backyard pond. But that doesn’t mean your pond has to look ugly or be hard to maintain. You simply have to cooperate with nature.


Do You Want to Grow Plants or Algae?

Why Pond Water Quality Matters

Understanding why pond water quality matters is fundamental. It's a direct reflection of how effectively you're managing your pond. For many novice pondkeepers, the initial excitement involves filling the pond with water, introducing fish, and adding a few plants. The joy of interacting with fish, especially during feeding when they eagerly gather around, often leads to overfeeding. Fish have voracious appetites and rarely decline food. However, overfeeding has two negative consequences. First, it causes fish to accumulate unhealthy fat deposits. Second, it introduces a detrimental element to the pond's ecosystem. 

How does this occur? Fish food contains proteins and essential nutrients like phosphorus. As fish digest their meals, some of these nutrients are released into the water. Additionally, when uneaten fish food decomposes, it also releases nutrients into the water. Interestingly, the primary beneficiaries of these nutrients are aquatic plants. But algae are plants too. 

Read more:  Pond Water Testing 101: Mastering Water Quality for Healthy Ponds


Do You Want to Grow Plants or Algae?

If you have a water garden the aquatic plants will remove the nutrients from the water and keep the algae in check. Over-feeding the fish is unhealthy for them and tips the “balance” toward excess nutrients in the water and stimulates algae growth. This is because the aquatic plants just can’t keep up with all those nutrients. Guess what type of plant is happy to step up and help eat up those excess nutrients? Algae!

Here are some essential points to keep in mind:

  • A balanced pond has enough plants to keep the nutrients low.
  • Over-feeding causes a nutrient imbalance.
  • Over-feeding makes fish fat and unhealthy.
  • Over-feeding causes algae to take over.


Achieving Nutrient Balance in Fish-Only Ponds

Achieving Nutrient Balance in Fish-Only Ponds

In comparison to water gardens, fish-only ponds face a constant challenge in maintaining nutrient balance. These ponds typically lack the presence of aquatic plants that naturally absorb excess nutrients. As a result, nutrients tend to accumulate in the water over time, creating an imbalance that can lead to water quality issues.

There are several strategies to address this nutrient imbalance. In small ponds, frequent partial water changes can help dilute the nutrient levels. However, this approach may be impractical for many pond owners, especially those with larger ponds. 

An alternative solution involves creating a separate planted pond or bog, which serves as a natural nutrient filter. In this setup, water from the fishpond is circulated into the planted area, where aquatic plants efficiently utilize the nutrients. The purified water is then returned to the fishpond, promoting a healthier pond environment.

Another method is the use of a UV clarifier to combat algae growth that often leads to green water. If you opt for a chemical algaecide, be sure to choose one that does not contain copper (a heavy metal), and always follow the manufacturer's instructions carefully, avoiding over-dosing. Natural barely based algae control products can also help but take about a month to work.


Water lilies

How Many Plants Do I Need?

The number of plants your pond requires largely depends on the two primary factors: pond size and plant type. The general rule is to try to have enough plants so that about 60% of the pond surface is covered. Water lilies and other floating plants work well. Plants that produce lush foliage will remove a lot of nutrients from the water. 


Managing Decaying Plants and Pond Sludge

Decaying leaves release nutrients back into the water. They also form a sludge layer on the bottom of the pond. If the sludge gets thick enough, it starts to “rot” and release nutrients. 

Some sludge is natural and even acts as a natural habitat for microscopic aquatic life. But a thick sludge coupled with too many fish and over-feeding often results in poor water quality and can even promote fish disease. 

Tip: Regularly trimming and removing dead or dying plants help prevent nutrient buildup and promote a balanced pond environment.


Keep the Water Pump and Filter Clean

Your pond's water circulation system, consisting of the pump and filter, plays a vital role in ensuring the health of your pond ecosystem. This system is responsible for several crucial functions, including providing oxygen to both fish and the countless microscopic organisms that work behind the scenes to break down fish waste, debris, and other pollutants.

Effective water movement helps oxygen diffuse into the water. However, over time, pond pumps can become clogged with various debris, such as leaf fragments. This accumulation not only slows down the water flow to your waterfall or fountain, but it also adds nutrients and undesirable organic compounds to the water. All that “dirt” in the filter is decomposing, using up oxygen, and releasing nutrients, potentially causing water quality issues.

To prevent these problems, it's crucial to regularly service your pump and filter. Routine maintenance removes trapped debris before it can decay and negatively impact water quality, ensuring a healthy and thriving pond environment.

Read more: Pond Filtration 101: A Comprehensive Beginner's Guide


Effective Pond Sludge Control Methods

We've discussed the topic of pond sludge a few times, and it's worth understanding how to keep it in check. A modest amount of soil and debris settling at the pond's bottom is a natural occurrence and poses no harm. However, allowing it to accumulate season after season can lead to issues.

If you have a small to medium-sized pond, a practical solution is to use a submersible solids pump to remove sludge once or twice a year, preferably during the fall. This time of year is ideal for cleaning out the muck and making a water change.

For pondkeepers with larger or deeper ponds, a specialized tool known as a pond vacuum comes into play. Similar in function to a shop vac but designed to work underwater, a pond vacuum offers an effective means of cleaning large ponds, preventing excessive sludge buildup and promoting a healthier pond environment.


Summary: Keeping Your Pond in Harmony

Creating and maintaining a balanced pond ecosystem  is not difficult. Now that you understand how to tip the balance toward healthy conditions, you’ll have an easier time keeping your pond beautiful. Just follow the principles outlined in this article and you’re sure to have success!

Key takeaways:

  • Recognize your pond type: fish-only or water garden.
  • Prioritize pond water quality by avoiding overfeeding.
  • Maintain a balanced pond ecosystem to reduce algae growth.
  • Promote balance with aquatic plants in your pond.
  • Trim dead plants to prevent nutrient buildup.
  • Keeping your water pump and filter clean.
  • Control pond sludge through seasonal cleaning.
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Thank you for your kind words, and best of luck with your ornamental pond! 😊

Ponding Time

Gosto muito de ler os artigos que vocês publicam. Tenho um lago ornamental no meu quintal e as instruções dadas através das publicações teem sido muito úteis pra mim!
Muito obrigado!

Geraldo Tadeu Rodrigues

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