DIY Pond Maintenance: 5 Mistakes That Can Cost You Big

When Melissa from Eden Prairie decided to build and maintain her own backyard pond, she had a vision: a serene retreat where her koi could thrive and where she could unwind after long workdays as a nurse. She spent hours researching, planning, and finally getting her hands dirty, excited to create her dream water feature. For the first season, everything seemed perfect. But by the next spring, Melissa started to notice problems: murky water, algae blooms, and a mysterious drop in her pond’s water level. Despite her best efforts to troubleshoot, her pond was more work than relaxation, and her koi began showing signs of stress as she started losing them one by one.

That’s when Melissa gave us a call at Superior Ponds. After inspecting her setup, it became clear that some common DIY missteps were causing these issues. By helping her address these 5 mistakes, Melissa was able to enjoy her pond the way she had always envisioned—peaceful, healthy, happy fish, and worry-free after long days at work.

If you’re a DIYer looking to care for your pond, here are five common mistakes to avoid, along with solutions to keep your water feature thriving.

Prefer to listen instead? Listen to Andrew and Emma of the Ponderings Podcast discuss this article below!

1. Underestimating Filtration Capacity

Filtration is the backbone of any healthy pond ecosystem. Many DIYers underestimate the filtration needs of their pond, especially if they have a high fish load (Like Melissa, most people always end up having too many fish for their original system). An underperforming filter can lead to an accumulation of waste and debris, resulting in poor water quality, algae growth, and fish stress.

What to Avoid:

Relying solely on a small out-of-the-box filter for a large pond.
Getting too small of a pond kit for the number of fish (pay attention to gallon size)
Forgetting to clean or maintain the filter.

Ensure your filtration system is sized appropriately for your pond’s volume and fish load. Aquascape Inc. recommends combining mechanical and biological filtration to remove debris and support beneficial bacteria. Do this by getting the right size equipment from the start, do not skimp on equipment quality when so much work is being put into your water feature. For Melissa with an undersized filter, this meant installing a biobowl filtration system with plants and a small water cascade to help with filtration and water oxygenation for her fish.

Additionally, make cleaning your filter a regular part of your maintenance routine to keep it functioning efficiently. Even the best filter won’t work if neglected!

2. Ignoring the Role of Beneficial Bacteria

So often neglected, beneficial bacteria is essential for maintaining a healthy pond ecosystem. These microorganisms break down harmful ammonia and nitrites from fish waste, decaying plants, and uneaten food. Many DIYers overlook the importance of regularly replenishing this bacteria, especially after cleaning their pond or during seasonal transitions, leading to water quality issues and imbalances.

What to Avoid:

Assuming beneficial bacteria occur naturally in sufficient quantities in a closed yard pond system.
Skipping bacterial treatments after cleaning or during periods of heavy algae growth.
Neglecting to regularly add beneficial bacteria treatments on a weekly basis.
Not installing an automatic dosing system to help with regular treatments.

Incorporate beneficial bacteria treatments into your regular maintenance routine. Adding these treatments after cleanings, during especially warm periods, and following heavy rain ensures a healthy population of bacteria to keep your pond balanced. The Minnesota Water Garden Society highlights that biological filtration, supported by beneficial bacteria, is critical for breaking down organic debris and maintaining clear water.

For Melissa, she had no idea that any water treatments besides a dechlorinator were needed. Once she added weekly dosings of beneficial bacteria into her maintenance routine, she said it was like magic watching the water begin to clear over just a couple weeks as the ecosystem began balancing itself.

3. Neglecting Seasonal Transitions

3. Neglecting Seasonal Transitions
Minnesota’s climate presents unique challenges for Minneapolis pond owners, with freezing winters and hot summers requiring seasonal adjustments. Many DIYers fail to properly prepare their pond for these transitions, leading to problems like winter fish kills or summer algae blooms.

What to Avoid:

Leaving equipment like pumps and filters in the pond over winter without proper shutdown.
Neglecting to aerate or de-ice the pond during freezing months.
Skipping major seasonal maintenance tasks like a spring cleanout and fall netting
Not adding cold water beneficial bacteria during the winter to help with sludge breakdown

Prepare your pond for seasonal changes by investing in equipment like de-icers and aerators for winter, seasonally appropriate beneficial bacteria treatments for summer and winter, basic pond cleaning equipment for spring, and a netting system for leaves in the fall. The Minnesota Water Garden Society emphasizes the importance of fall cleanup and winter preparation to prevent debris from decaying under the ice and depleting oxygen levels, because a good season in the pond starts with the right fall and winter shutdown the year before.

Proper seasonal care protects your fish and reduces the workload when spring arrives.
Melissa’s first year in the pond was a good one because she was starting with a fresh slate. When her second year rolled around with a full carpet of leaves on the bottom of her pond and no spring cleaning, the issues simply began to multiply. Getting a pond cleanout took all the nasty decomposing sludge out and allowed her pond to regulate itself without the bio-overload.

4. Overfeeding Your Fish

Feeding fish is one of the most enjoyable aspects of pond ownership, but overfeeding is a common mistake that can have serious consequences. Excess food breaks down into ammonia, contributing to poor water quality and algae growth. Fish can also develop digestive issues from overeating, especially during cooler months when their metabolism slows. And fish who get full on fish food don’t help eat any algae in the pond.

What to Avoid:

Feeding more than your fish can consume in under 5 minutes (2–3 minutes is ideal).
Feeding multiple times a day.
Continuing to feed during the winter when fish enter dormancy.

To avoid these issues, feed only what your fish can consume in a few minutes and resist the urge to overindulge them—it’s better for their health and your pond’s overall balance. Melissa loved feeding her fish, and would toss them food every chance she could get which ultimately led to unhealthy fish in an unhealthy pond. We showed her how to measure their food out and enjoy the feeding process more by throwing in smaller bits than large handfuls at a time. Trust the natural cycles of your koi and goldfish—they’re more resilient than you might think!

5. Underestimating the Workload

One of the last of the 5 most common mistakes DIYers make is underestimating the time, effort, and expertise required to maintain a pond. From annual cleanings to seasonal transitions, regular filter cleanings and adding water treatments, keeping your pond in top condition can feel like a full-time job. According to the National Association of Landscape Professionals, homeowners with professionally maintained water features report a 37% increase in overall enjoyment and use of their ponds. This is why Melissa called, because she was tired of what seemed like a full-time job with her pond after her full-time job at the hospital. DIY solutions that work temporarily often require ongoing troubleshooting, leading to more stress than relaxation.

What to Avoid:

Undersizing the equipment for your system, leading to ongoing maintenance burdens
Not having a regular maintenance schedule, because letting go for too long leads to more problems.
Taking on more maintenance than you have time for.
Learning on the fly, not investing the time before you start to understand how a pond ecosystem works.
Overlooking professional guidance that could save you time and money.

If you’re struggling to keep up with your pond’s needs, partnering with a professional can make all the difference. This doesn’t mean giving up complete control—many DIYers benefit from a simple evaluation to get expert recommendations tailored to their setup. By leaving the more complex tasks to experts, you can avoid costly mistakes, reduce stress, and focus entirely on the joy your water feature brings—a true backyard retreat.

Why This Matters for You

A pond should be a source of peace and beauty, not frustration. By avoiding these common DIY mistakes, you’ll protect your fish, maintain a healthy ecosystem, and save time and money in the long run. Whether it’s investing in better filtration, transitioning with the seasons, or adjusting your feeding habits, small changes can make a big difference.

How Superior Ponds Can Help

At Superior Ponds, we understand the unique challenges Minnesota pond owners face, and we’re here to help. From complete seasonal maintenance to filtration upgrades, providing treatments and installing automatic dosing systems, training with fish care and algae control, we offer customized solutions to fit your needs. With our Clear Water Guarantee included for our VIP Maintenance Members (hands-free water maintenance for our clients), you can rest easy knowing your pond is in good hands—leaving you free to enjoy your tranquil retreat without the hassle.