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Help! There are a bunch of dead fish in my pond, what happened? | Pond & Lakes Q&A

Why do frogs/toads make so much noise?

Help! There are a bunch of dead fish in my pond, what happened?
Jason – Hastings, NE

The arrival of spring is an exciting time for pond owners. The weather is warming up, the sun is shining and the ice is melting away from the surface of your pond. Some pond owners however, find all of their fish floating dead at the water’s surface. While experiencing a winter fish kill is not the best way to start the season if you understand the cause you can prevent future occurrences.

Your pond is constantly absorbing and releasing air. As wind blows across the surface of the pond water ripples absorb oxygen into the water column. Decomposing organic debris at the bottom of the pond release a gas that floats to the surface of the pond where it is released into the atmosphere.

The layer of ice that forms over your pond blocks air exchange locking fresh oxygen out of the pond and harmful gas from decomposition in. Depending on the size of the pond and the amount of decomposing debris available, your fish can be overwhelmed and killed by the lack of fresh air.

Fish kills can also happen in the summer. Summer fish kills are typically caused by pond turnovers due to lack of proper aeration. The top layer of water in your pond carries more oxygen and reacts faster to temperature changes due to its exposure to the air. The bottom of your pond will tend to contain less oxygen, light and will be slower to warm up throughout the summer. These layers of water are referred to as stratification and are divided by thermoclines. If you have ever swam in your pond you may have noticed that your feet are colder than your chest as they break the thermocline in the water column. Your fish will find a happy medium in the water column where there is adequate oxygen and warmth.

Particular rainy or windy days can cause the thermocline in your pond to break. The bottom layer of water in your pond will mix together with the healthier top layer of water. As your fish have nowhere to flee to, they are trapped in the newly mixed pond water which can severely stress and even kill your fish.
Fortunately, there are a couple of ways to prevent winter and summer fish kills. An Bottom Diffused Aeration System like the Airmax® AM Series pumps fresh air to the bottom of your pond and breaks it into fine bubbles that can be absorbed into the water column. As the air bubbles rise through the water column they also circulate the water body making sure that your pond is evenly oxygenated and warmed. An abundance of oxygen promotes the presence of beneficial aerobic bacteria which will help break down organic waste faster and without the egg-like odor produced by the slow anaerobic bacteria in water that lacks oxygen. Running an aeration system in the winter can also eliminate your winter fish kills as the constant bubbling at the surface of your pond prevents ice formation and quickly breaks up layers of ice.

To further aid in your fish kill prevention, you will want to remove as much organic debris from the bottom of the pond as possible. Beneficial Bacteria products like PondClear™and MuckAway™ in tandem with EcoBoost™ will naturally digest gas and algae causing muck without having to chemically treat your pond. Cut down and drag away any dead cattail reeds and leaves with a Weed Cutter and Rake so that they are not left to decompose. The Pond Logic ClearPAC® Plus combines all the beneficial bacteria products you need along with pond dye and an option algaecide to eliminate the guesswork of selecting the proper pond care products.

Pond Talk: Did you find any surprises under the ice in your pond this spring? What are you doing to resolve the issue?

Aeration

I shut my aerator off for the winter, will I have to introduce it slowly again in the spring? | Pond & Lakes Q&A

I shut my aerator off for the winter, will I have to introduce it slowly again in the spring?

I shut my aerator off for the winter, will I have to introduce it slowly again in the spring?

George – Albany, NY

As pond owners we buy aeration systems for our water bodies with the intentions of creating a cleaner and healthier environment for both ourselves and our fish. While aeration systems are great at eliminating water stratification and promoting the ideal environment for a healthy pond, the key to proper use is proper installation.

The surface of your pond reacts to the ambient air temperature and warmth from the sun considerably faster than deeper regions. As we head into spring the temperature will begin to rise as the sun shines down on your pond. The top layer of water in your pond will begin to warm up quickly while the bottom of your pond stays dark and cold. Furthermore, the surface of your pond is exposed to oxygen which is naturally wicked into the water column but remains only in the upper layers. This formation of warmer and cooler layers of water is known as stratification. Stratification can become a potential hazard as the two different layers of water will sometimes flip or “turnover” and mix together causing a sudden change in water temperature and dissolved oxygen levels which, depending on its severity, can make it difficult for your fish to adapt to the quickly changing environment.

Airmax Aeration Systems are designed to infuse oxygen into your water column from the bottom of the pond while continuously circulating the water. This constant action aids to prevent water stratification for occurring. However, when aeration is introduced suddenly and continuous to your pond you are, in essence, creating a man-made turnover by forcing all of the water at the bottom of your pond to the surface.

When installing an aeration system in your pond, or upon reintroduction of your system after winter removal, you will want to run your system in small increments that grow in duration over the course of a week. Think of this process as the same way you acclimate new fish to your pond. You wouldn’t just grab a new fish by the tail and toss them in your pond, you float their holding container in your pond and slowly mix some of the water together to give them time to adjust to the variations in each environment. By running your aeration system for only an hour the first day you install it and doubling the run time each day after, your aeration system will be running continuously by the end of the week while keeping your fish safe from pond turnovers.

Pond Talk: Have you ever experienced turnover in your pond? Share your stories with potential aeration newcomers and pond veterans alike.

Keep your pond healthy all year long!

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