Can You Have Too Much Flow in a Pond?

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A fish pond is a perfect addition to your garden or yard. It can be a relaxing spot to hang out or an exciting major feature in your garden. Looking at your pond, you may wonder if you can have too much flow in it?

Ponds can have too much flow. If the pond has too much flow, it could eventually harm the fish and plants living in it. Too much flow will cause excessive wear and permanent damage to the water pump. Calculate the correct amount of flow by finding the volume of the pond.

Running a pump in your pond is important to improve the oxygen levels in the water. While increased oxygen levels are necessary for organic life in the pond, too much flow can cause serious harm. Keep reading to learn about why flow is important, and how much flow your pond needs based on its size.

Damage from Too Much Flow

Too much water flow can cause damage all over your pond. For smaller ponds, too much flow can make your pond too intense and immediately uproot plant life and injure or kill fish. With bigger ponds, too much flow will begin to damage plant life and injure fish at most. However, over time the fish may not be able to find a place to rest and will eventually die.

The best way to tell there is too much flow in your pond is by listening and looking at it. If it is loud all the time, there is too much flow. Looking at your water; if it is rushing too much, the water is loud, water squirts out, or spills over the edge then there is too much flow. Looking at how plant and fish life are doing is a good way to see if there is too much flow.

If the plants look like they are being blown over by the current of the water, turn down the flow. Additionally, if it looks like the fish are searching for a place to rest, turn down the flow.

Besides direct damage to your pond, too much flow can cause damage to the pump itself. The pump may be overworking itself, which can cause it to break easily and deteriorate faster. The more your pump is working, the more power it is going to use and the more wear it is going to endure. This means that your power and maintenance bills will increase.

Creating Good Flow

Creating a good flow in your pond is very important and it is not as difficult as it seems. Your pump and filter sizes should be equal to the water volume of the pond. To calculate water volume you need to multiply the length of your pond times the width, then times the depth. Finally, multiply that number by 7.5 because each cubic foot of water has 7.5 gallons in it.

For example, if your pond is 10 feet wide, 15 feet long, and 2 feet deep, your pond has a water volume of 2,250 gallons. This means that your pump and filter sizes should be 2,250 gallons per hour (gph) for the pump and 2250 gallons for the filter. With these settings, it will take an hour to cycle out all of the water in the pond. However, this rate will vary by the pond and what you have in it. For example, in a Koi pond, your flow rate will equal your pond’s volume. But for a goldfish pond, you divide the volume by 1.5 and for a nature pond, you divide the volume by 2.

Following this method creates an average amount of flow that will not hurt plant or fish life. If you want your water to be a little more rushing, to give your pond some extra life, you can double the pump output. So instead of 2250 gph, it would be 4500 gallons per hour. However, be very cautious when doing this. Continually look for signs of too much flow for several days after increasing the flow of your pond.

While aesthetics and sound are important factors when choosing the flow in your pond, remember, the primary reason for aerating the water is to increase the dissolved oxygen levels.

For your pond to support organic life (ie. fish and plants), it needs adequate dissolved oxygen. Standing water tends to have low oxygen levels, aerated water flow can revitalize the water’s oxygen levels. As you set the flow of your pond, pay attention to the organic life inside of it.

Ever wondered if you can aerate your pond with a Waterfall? Check out my article here.

How to Keep Flow in the Winter

If fish and plants are living in your pond, they need oxygen to survive year-round. However, in the winter months, running a pump to create flow becomes increasingly difficult.

As the temperature drops, the surface of your pond will start to freeze. Once the surface of the pond is frozen solid, the pond’s only access to dissolved oxygen is through underwater plant photosynthesis and groundwater.

But what if your pond has neither of these things? Will the organic life die?

The short answer is no. Coldwater retains more dissolved oxygen than warmer water. In other words, the colder water in the pond begins collecting more oxygen as the temperature drops. Though the pond may be sealed from the surface there is still oxygen under the surface.

If the oxygen levels are depleted (by algae or other means), the pond will become anoxic. Plants and fish cannot live in these circumstances. So how do you prevent algae blooms from sucking the oxygen from your pond this winter?

First of all, you do not need to remove all the algae from your pond. During the winter months, fish will snack on this plant to survive. In other words, it is a crucial part of your pond’s food chain.

That being said, you can reduce algae blooms by growing other aquatic plants or by removing surface blooms as they appear. Though you could use algaecides to remove the algae, this is not suggested as it will strip the fish’s food source from the pond ecosystem.

While you do not have to keep a continual flow in your pond through the winter, it would be wise to break open the ice every other day or so. Doing so will allow the pond to release stored CO2 levels and absorb more oxygen.

If you do want to run your pump through the Winter, you may need to run a water heater as well. As the water in the pond gets colder, it could freeze the pump. If the pump freezes, it could sustain significant damage.

In most cases, it is best to avoid winter damage by storing the pump in a warm, dry place until Spring comes. However, if you choose to run your pump through the winter, perform frequent maintenance and keep it warm.


I am always happy to share all my knowledge about how to keep your garden in good condition and make it special.

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