How Do You Know If There Is Enough Oxygen In Your Pond?

In this article, you’ll learn how to tell if your backyard pond has enough oxygen, how to test your pond for oxygen as well as some great tips on how you can ensure the oxygen in your pond is at healthy levels in the summer and winter.

Let’s begin.

Equipment To Oxygenate Your Pond

  1. Pond Oxygen Tablets

How Oxygen Concentration Affects the Fish in Your Pond

Fish utilize the oxygen that’s dissolved in pond water and not from the air around the pond. Any changes in the oxygen concentration of your pond water will affect the fish in the pond drastically.

Low oxygen concentration can lead to fish death if not addressed on time. Low levels of oxygen put the fish under excessive stress. Fish stress affects the overall well-being of the fish. There’s only a certain limit of stress that fish can bear. Beyond that, the situation can be fatal, and the fish will die.

Signs that Your Pond Has Enough Oxygen

You can quickly tell if your pond has enough oxygen.

  • If the oxygen levels in pond water are adequate, your fish will appear happy, active, and healthy.
  • Your pond will be clean. There won’t be any excessive algae growth that makes a pond look dirty and unkempt.
  • You won’t observe any foul or lake-like odor coming from your pond.

Signs that Your Pond Doesn’t Have Enough Oxygen

The signs that your pond doesn’t have enough oxygen are hard to miss. Below are some of the most prominent signs that will tell you that you need to adjust the oxygen levels in your pond right away:

  • Fish will come to the surface to breathe. You’ll either see the fish on the surface of the pond, struggling for oxygen, or near any water features. They’ll appear restless.
  • Your pond will give off a foul odor. Excess fish waste and decaying of vegetation and other organic matter will give off a strong odor if there’s insufficient oxygen in your pond. The smell will be similar to what natural lakes smell like.
  • You’ll observe a thick layer of algae growing on the surface of the pond. Excessive algae growth suggests high levels of carbon dioxide and low levels of oxygen in the water.

What Causes Low Oxygen Levels in Ponds?

Numerous factors can result in low levels of oxygen in ponds.

  • One of the primary causes of low oxygen levels in pond water is an overcrowded pond. If the pond has too many fish, the oxygen consumption will be higher than the oxygen production, leading to deficient oxygen levels.
  • Weather plays a critical role in this regard. The level of oxygen in pond water is usually lower in summers because warm water is believed to hold less oxygen when it’s hot. Suppose the weather is rainy or there’s overcast for prolonged hours during the day. In that case, the oxygen level can get affected as the pond plants do not get enough sunlight to photosynthesize – the primary source of oxygen for pond fish and other pond organisms.
  • Excessive death of pond plants can also lead to oxygen depletion since the number of plants performing photosynthesis to produce oxygen is reduced.
  • A high level of organic matter can also cause oxygen levels to drop.

What You Should Do if Your Pond Has Low Oxygen Levels

If you suspect that your pond has low oxygen levels, you need to do something and do it fast. Some of the things that you can do to replenish the oxygen in your pond water are:

  • Spray water into the pond using a water hose. A jet spray over the pond not only adds oxygen to your pond, but the pressure also displaces the chlorine and makes pond water safe for the fish.
  • Break the water surface repeatedly, which will make way for the addition of oxygen to the water. You can do so by adding a fountain to your pond.
  • One of the most effective ways to combat low oxygen levels in your pond is to install a pond air pump that will pump air over the water’s surface, breaking the water surface continuously to add oxygen to pond water.
  • You can also introduce some plant varieties in your pond that produce reasonable quantities of oxygen.

How to Measure and Test if Your Pond Has Enough Oxygen

Keeping a check on the dissolved oxygen levels in pond water is critical for pond fish’s well-being. When the dissolved oxygen level falls below 2mg/liter, the situation becomes lethal for the fish.

While you can keep an eye out for the signs of low oxygen levels, you need to use a more quantitative method for an accurate measurement. One way to measure and test if your pond has enough oxygen is by using a pond oxygen test kit.

Use a Pond Oxygen Test Kit

A pond oxygen test kit is a quick and reliable way of testing the oxygen levels in a pond. It is a set of reagents that measure how much oxygen is in the water. Using a pond oxygen test is pretty simple.

  • Collect a sample of water from the pond. Submerge the sample bottle entirely in water and seal it while still submerged to ensure no air makes its way inside.
  • Add magnesium sulfate, followed by alkaline iodide azide – both of these are included in the test kit – to the sample water and shake the bottle gently. You’ll see a brown-colored floc forming in the water. Allow this floc to settle.
  • Add sulfamic acid (also included in the kit) and shake the bottle again. This will dissolve the floc, and the sample will turn yellow.
  • Add the stated volume of water and chemical mix in the mixing bottle and add sodium thiosulfate drop by drop while swirling it. Stop when the water turns clear again.
  • Dividing the number of drops of sodium thiosulfate by two will give you the value of dissolved oxygen in mg/liter.

Using a pond oxygen test kit may sound tricky, but it’s pretty straightforward, reliable, and fast.

How to Measure Pond Oxygen in Winter

Maintaining pond oxygen in winter is extremely important. While cold water holds more oxygen and fish and plants in the pond utilize less oxygen in winters, the pond can still fall short of oxygen, especially if your pond surface freezes.

It’s necessary to keep a small area of your pond open so that the gas exchange doesn’t come to a halt. If you live in a place where the temperature falls too low and the pond surfaces freeze to form thick ice, you may even have to install a pond heater or de-icers to maintain an open area throughout the winter. Or, you can also opt to use an aerator during the winter or keep your pump running all winter to help keep oxygen levels safe.

Whatever measures you take to maintain pond oxygen in winter, you still have to keep a check on the numbers. You can measure pond oxygen in winters the same way you would do in summers – using a pond oxygen test kit.

Using the test kit won’t be a challenge as long as there’s an open area available on the pond surface. You can collect the sample easily and test it using the reagents given in the kit.

How to Increase Oxygen Levels in Your Pond

If the pond oxygen levels are low, you should immediately work towards setting it right.

So, How do you increase oxygen in a pond?

There are numerous ways in which you can increase the oxygen level in your pond.

  • Introduce suitable types of plants to your pond, like submerged and floating plants that increase the oxygen level and maintain a healthy pond environment.
  • Remove the muck and decaying organic matter routinely as it uses up the oxygen in pond water.
  • Install a pond air pump
  • Introduce water to your pond using a spray jet.
  • Use oxygen-enhancing pond products.

Use an Oxygen Pump

You can use an oxygen or air pump to increase the level of oxygen in your pond. It’s installed over the pond’s surface, to the side, where it pumps air into the water through a hose to an air stone. Bubbles break the surface of the water, and the air is added.

An oxygen pump ensures that a small part of the pond stays open to exchange gases when the rest of the pond surface is frozen.

Solar Powered Floating Pond Oxygenators

Solar-powered floating pond oxygenators are the best type of oxygen pumps for your pond. They’re floating pumps with a solar panel. It absorbs sunlight and uses it as a power source. It’s not stationary like regular air pumps. It’s a wireless device that moves across the pond and oxygenates different parts of the pond.

The more sunlight, the more oxygen it’ll pump into your pond. It has an air stone attached to it that spreads bubbles across the pond and ensures that the entire pond is oxygenated sufficiently. There’re no running costs involved.

Not only does a solar-powered floating pond oxygenator adds oxygen to your pond, but it also prevents the growth of algae over the pond’s surface. It keeps your pond clean and clear and ensures it’s adequately oxygenated for the pond fish.

Oxygen Stones

Oxygen stones are heavy, porous stones that produce tiny bubbles in the water. It’s a relatively simple accessory that has an extraordinary impact. It diffuses air in the pond gradually, ensuring that the water has sufficient oxygen. Oxygen stones produce agitation in the water needed to increase the level of oxygen in the pond water.

How to Provide Oxygen Naturally without a Pump

If you don’t have an air pump or don’t want to invest in one, you can still provide oxygen to your pond naturally. Some of the simplest yet highly efficient ways of doing so are listed below:

  • Cup Method

The cup method is more suitable for an aquarium, but you can use this technique with some modifications for your pond.

Fill a bucket with water from the aquarium, raise it high, and pour the water back in. The water will absorb oxygen from the air on its way back, and voila – you just added oxygen to your pond without using a pump.

It’s suitable only if your pond is small in size and not too deep.

  • Waterfall Filters

You can install pond waterfall filters. The pond waterfall filter will keep the flow of water continuous. It’ll pour down the water in the pond like a waterfall, and the flowing water will catch oxygen on its way back and oxygenate the pond.

  • Add Oxygenating Plants

Add plant varieties to your pond that use up a lot of carbon dioxide and produce oxygen. The more plants there are, the more will be the oxygen level in your pond.

  • Oxygen Tablets

Oxygen tablets enhance the amount of oxygen that’s available for fish and plants. They release oxygen in pond water efficiently in a controlled manner that ensures a sound pond environment all the time.

Use Pond Oxygen Tablets

Oxygen tablets are special tablets that release oxygen when added to water. They are made primarily of hydrogen peroxide along with different sodium compounds. Hydrogen peroxide is highly reactive when it comes in contact with water and releases oxygen rapidly.

The oxygen is produced as a stream of tiny bubbles that create the required agitation in pond water and adds oxygen, giving the pond water an instant boost in oxygen levels.

Use Oxygenating Plants

Oxygenating plants are rapidly-growing plants that produce a reasonable amount of oxygen into the water. Although all plants produce oxygen, some plant varieties produce more oxygen than others.

Ranunculus aquatilis, or water-crowfoot, is the most suitable variety of oxygenating plants for winter and spring. Ceratophyllum demersum or hornwort and waterweed are ideal for the autumn or summer seasons. Other popular types of oxygenating plants include Hottonia palustris or water violet and Hippuris Vulgaris or mare’s-tail.

What is the Best Way to Aerate Your Pond?

The best way to aerate a pond is to install an aeration system. A subsurface aeration system adds diffused air directly into pond water. This type of aeration system works bottom-up.

It uses a compressor to pump the air to the bottom, and the diffuser produces tiny bubbles that rise to the surface. This way, the pond stays aerated, and the levels of oxygen in pond water are maintained within a healthy range.

You may also use a pond aerator that is installed over the surface of the pond. It produces agitation over the pond’s surfaces and mixes the top layer of water with oxygen from the surrounding air. Fountains are an example of surface aeration.

Video: Do you have enough Oxygen in your pond?

Watch this video from Koi TV where they show you how to do an easy test.


How do I check the oxygen level in my pond?

The best way to check the oxygen level in a pond is to use a test kit. Simply place the test kit bottle into your pond until there aren’t any more bubbles. Then remove the test bottle follow the test instructions and wait for the results.

How do I know if my pond needs oxygen?

You can tell if your pond needs oxygen by looking at the fish. If the fish are gasping at the surface for air there is a good chance they need oxygen. When testing it’s best to aim for 6mg/liter of dissolved oxygen in your pond.

Does rain add oxygen to a pond?

Yes; rain can increase oxygen in your pond. As rain falls into your pond, it causes surface agitation, allowing oxygen to enter the pond water. Rainwater is also a clean source of water and contains small amounts of dissolved oxygen.

Do Weeds Produce Oxygen in Your Pond?

Yes. Pond weeds produce oxygen, much in the same way as other plants – through photosynthesis. They utilize the carbon dioxide in water and make sugar and oxygen.

Does Algae Produce Oxygen in Your Pond?

Microscopic algae or phytoplankton are often the primary sources of oxygen in a pond. They utilize carbon dioxide and produce oxygen.

What Happens to the Available Oxygen for Your Fish if You Have too Much Algae?

Too much algae in the pond can be harmful to the fish. Although algae produce oxygen, like all other plants, they produce carbon dioxide during the night. Too much algae means too much carbon dioxide, leading to oxygen depletion and excessive fish stress – leading to fish kills.


Jack Dempsey