Dissolved oxygen is essential for air-breathing koi, goldfish, snails and tadpoles. But did you know that our water gardens and koi ponds “run” on oxygen? That’s right!
The billions of microscopic bacteria and other microbes that eliminate harmful wastes, like ammonia, need oxygen to live and keep the water clean and safe for pond life. Without oxygen, our fish will suffer, get sick or die.
The water would quickly become too toxic for aquatic life. That’s why we use aeration devices to make sure the water contains enough dissolved oxygen to keep our pond healthy.
FAQs about ponds, oxygen and aeration
Have questions about your pond and aeration? Below are the most common questions about oxygen and aerating a pond. Chances are you’ll find your answer here.
How does oxygen get into ponds naturally?
Oxygen (O2) is a gas present in the atmosphere. It will naturally diffuse into ponds, lakes and streams. Plants and algae also release oxygen into the water during the day.
Why do I have to aerate my pond?
Backyard ponds contain a much more dense population of oxygen-consumers than natural lakes. Most of the oxygen that naturally diffuses into your pond is used up by the bacterial and chemical processes that work to keep the pond clean and balanced.
Fish waste and other organic matter builds up on the bottom and forms a sludge layer. Microorganisms on the bottom of the pond digest this organic matter and use up the available oxygen.
Plants and algae use oxygen in the night time. Goldfish, koi and other air-breathing pond creatures also consume oxygen.
Without man-made aeration, there won’t be enough oxygen to satisfy the needs of all the aquatic life.
What if there is not enough oxygen in the pond?
The first thing you’ll notice is your fish gasping at the surface.
Keep in mind that all pond fish will gulp air from time to time. But when they are suffering from low oxygen conditions, they will become very lethargic and continually pump their gills at the water surface.
The bacteria and other microbes that keep the ecosystem balanced need oxygen but will just slow down their activities when oxygen is low. This means they won’t be working as hard to keep the pond clean and healthy.
In hot weather my fish gasp at the surface.
Water temperature and oxygen level are inversely related. That means the warmer the water, the less oxygen it can hold.
The pond may contain enough oxygen in the morning but not during the warmest part of the day or during extended warm weather. Oxygen levels can drop at night too. The plants and algae that make oxygen during the day, consume oxygen at night.
Will a fountain aerate my pond?
Research shows that hobby-sized fountain heads and surface splashing from waterfalls are the least effective ways to increase the dissolved oxygen in backyard koi ponds and water gardens.
Professional lake aerators send massive amount of water several feet into the air in order to effectively aerate the water. These devices are too large for backyard ponds and water gardens.
How do I make sure my pond has enough oxygen?
Pond aeration devices are designed to increase the dissolved oxygen in the water without disturbing the tranquility of the pond.
A pond aeration kit will ensure the pond water always contains enough dissolved oxygen.
How do pond aerators work?
Waterfalls and fountains are mostly for aesthetics but do slightly increase the dissolved oxygen by agitating the water surface. Surface agitation helps oxygen dissolve into the water.
Pumping air into the bottom of the pond is the most energy-efficient and effective way to aerate a backyard pond. Aeration kits include an air pump and an air diffuser device. The diffuser is placed on the bottom of the pond.
Compressed air from the air pump is pumped through an airline and down to the diffuser. The air bubbles come out through the diffuser and rise to the surface. When air bubbles are released at the bottom of a pond they naturally rise towards the surface of the water. As the air bubbles travel up to the surface, a slight current begins to develop.
The current pulls oxygen-depleted water from the bottom, oxygenates it and brings it to the surface. When the air bubbles reach the pond's surface, a gentle “boiling” motion is created. This motion circulates the water and also drives noxious gases like hydrogen sulfide (rotten egg odor) and carbon dioxide out of the water.
Should I run the aerator 24-hours a day?
Yes. Chronic low dissolved oxygen levels will stress the fish, weakening their immune system. This increases their susceptibility to illness and causes the fish to get sick.
Waiting until you see symptoms of oxygen deprivation is not recommended. Run the aeration system day and night to ensure the pond has enough oxygen.
Six Best Rated Pond Aerators Listed
If you’re considering adding an aeration system, check out these pond aeration kits. They’re easy to set-up, won’t use much energy and will ensure your pond will always have enough oxygen for the fish. Since the entire biological ecosystems depends on oxygen, you’ll be helping your pond or water garden stay clean, clear and healthy!
This pond aeration kit is designed for small backyard ponds.
The kit comes with an air pump, 6.5 feet of airline hose, one diffuser and a 1.5-watt solar panel.
The air pump is powered by the solar panel.
This means the air pump can only work when the sun is out.
On cloudy days, the air pump produces less air. At night, the pump stops completely.
- Small air pump does not take up a lot of space.
- Ideal for a small pond without a lot of fish.
- Solar power eliminates the need for an electrical outlet.
- Air pump will not work at night.
- Efficiency declines in the morning, evening hours.
This twin-diffuser pond aeration kit is designed for medium-sized ponds up to 5,000 gallons.
The kit includes a duel outlet air pump, two 25-foot airlines and two diffusers.
The diffusers can be positioned together or spaced apart on the bottom of the pond.
The airlines have built-in check valves that protect against water backflowing into the air pump. The rubber base on the air pump reduces vibration noise.
- Two diffusers for efficient aeration.
- 25-foot airlines make it easy to place the diffusers anywhere.
- Quiet air pump.
- Uses only 6 watts of electricity.
- 3-year warranty.
- None for the intended use.
The Aquascape Pro 60 is a heavy-duty aeration system for koi ponds and water gardens up to 10,000 gallons.
The air compressor is rated to produce 2.1 cubic feet of air per minute at a pressure of 5 psi.
The kit comes with an eight-inch diffuser dish.
The wide diffuser produces millions of tiny air bubbles for maximum aeration.
Also included is 30-feet of 3/8" braided aeration tubing to connect in between the compressor and diffuser. The extra-strong tubing resists kinking and tears.
The compressor has a built-in check valve to prevent water from back-flowing into the unit. The unit is built for wet environments but it is recommended that it be kept in an area protected from rain and dust.
- Plenty of flow for deep ponds.
- Heavy-duty compressor.
- Comes with a nice diffuser.
- Built-in check valve.
- Tubing is somewhat stiff compared to more flexible tubing.
The Danner AP-20 air pump is a high-volume air compressor designed for running one or more air diffusers.
This is not an aeration kit. The pump uses 5/8” I.D. tubing but it is not included with the air pump.
The pump can run a diffuser at a maximum depth of seven feet.
Rubber feet act to dampen noise and vibration.
The AP-20 has a flow rate of 1700 cubic inches per minute at 4 psi. If more air is needed, higher-powered models are available.
- Pumps a lot of air.
- Can pump air into deep ponds.
- Reliable operation.
- 6-foot power cord.
- You’ll need to purchase your own airline.
Rated for ponds between 1,000 and 4,000 gallons, the KoiAir Mini aeration kit is an all-in-one kit that contains everything you need in one box.
The kit comes with an 0.8 cubic feet per minute air compressor, 15 feet of weighted airline and a plate-style diffuser.
The plate diffuser is heavy enough to sit securely on the bottom of the pond. The air compressor is capable of pump air to a depth of four feet.
More powerful models are available.
- Complete aeration kit.
- High-quality tubing will not float or be disturbed by fish.
- Heavy-duty diffuser.
The Aspen Aeration kit is designed for extra-large koi ponds and 1-acre farm ponds.
The compressor is a powerful ¼-horsepower oil-less rocking piston unit with a 2-way air manifold complete with a pressure gauge.
A pressure relief valve protects the pump in case of accidental airline kinks or clogged diffusers.
The kit also included two 100-foot rolls of 3/8" weighted tubing that stays put under water. The airline won’t kink and is safe to use in freezing waters. Two 9-inch professional air diffusers have raised bases that keeps them above sludge and muck layers.
- Very powerful aeration system for large koi ponds.
- Professionally designed.
- Heavy-duty construction.
- Comes with a pressure gauge.
- Higher energy use.
- Nosier than smaller pumps.
All of these aeration kits and air pumps work as intended. The main consideration is matching the air pump’s output to your needs.
The Aspen Aeration kit is a very large, professional aeration kit intended for large ponds. It would be too large for the typical backyard water garden or koi pond. However, if you have a big koi pond full of large koi, this may be the perfect aeration kit for you.
For most backyard pond-keepers the AirMax KoiAir will probably do the job. It is a complete with that has all the components you’ll need to aerate your pond.
If you’ve got a small container pond or whisky barrel with a goldfish or two, the Beckett solar-powered aeration kit will provide enough daytime aeration and run the air pump by the power of the sun!