The Best Koi Pond Filters of 2021


Are you looking for the best koi pond filters? The koi fish are renowned as the living jewels of water gardens. Their striking beauty and elegance have symbolized success and advancement in life. Its unique name has Japanese roots, “nishikigoi” which means brocaded carp. These shining jewels surely are a treasure in every household and their beauty is greatly enhanced as they swim along and when they herd together. Taking only a few minutes each week for the elegance and exquisiteness they bring; they are worth keeping for a lovely home.Their ponds are not that hard to maintain, especially if you use koi pond filters. To choose one, get started with the following.

What is the Best Koi Pond Filter

Top 8 Best Koi Pond Filters Reviews

1. SUN CPF-2500 Grech Pond Bio Pressure Filter UVC Sterilizer up to 1.600 Gallons


Keep your koi pond crystal clear with this SUN CPF-2500. This filter is suitable for a mix of fish and koi up to 900 gallons and for decorative ponds up to 1600 gallons. It is one of the latest generation pond filters with biomechanical filter chambers for proficient solid waste removal.

Among its best features is the quick handle cleaning system, so you won’t need to open the foam all the time. It is UV integrated which alters algae component forming large particles for easy removal. A set of inlet and outlet hose adapters comes with the product so it easily maintains a healthy habitat for your beautiful aquatic creatures.

Bear in mind that the pump does not come along with the supply and the pressure may be too powerful, so you need to ensure you have the right volume capacity. Replacement sponge filters are also not included in the bundle but are widely available.


  • All connections found at the top cover
  • Compact and concealed design
  • Has an integrated UV unit
  • Keeps dirt in the filter and can be easily removed
  • Easy to maintain and clean


  • Pressure may be too powerful

2. Goplus Pressure Bio Filter for Koi Pond up to 4.000 Gallons


Rely on a durable koi pond filter with a superb performance with the Goplus Pressure Biol Filter. This filter body is made to last under the heat of the sun, with water and against aging with its high-quality ABS material. It also saves you time with its automatic cleaning mechanism, so you won’t need to open the container all the time.

High-quality sponges for the filter are also included for its multiple filtration mechanism, with two zones of high and low flow speeds. The water inlet and outlet also cater to different hose sizes. It is equipped with a UV bulb to ensure that you have healthy and clean water for your koi pond.

There may be no indicator light to confirm that the UV light is turned on. It has a dim glow which may confuse you that the UV bulb may not be included, but it works generally well.


  • Durable material
  • High quality filter sponges
  • Built-in UV bulbs
  • Easy to clean and maintain
  • Fits in to different hose sizes


  • No UV light indicator

3. TetraPond Bio-Active Pressure Filter with UV Clarifier up to 2.500 Gallons


Be at ease knowing that your pond is clean and healthy with a filter brand that has been trusted for years. TetraPond Bio-Active Pressure Filter with UV Clarifier delivers mechanical and biological filtration to ensure your koi and other fishes are thriving well.

It has an open profile bio-activator for better-quality cleaning –debris and grime are removed, leaving helpful bacteria intact. It also comes with a UV clarifier bulb to disrupt algae reproduction, clump them together for easy removal by the bio-activators. A unique backflush valve for fast cleaning. This works best for ponds up to 2500 gallons.

The backflush may need to be capped when not in use as it may automatically drain your pond. The feature, however, is very useful for fast and efficient pond cleaning where water is forced down creating a whirlpool effect in the bioactivation chamber and is later discharged out the backflush port with ease.


  • Has a biomechanical filtration system
  • Integrated UV clarifier
  • Uses bio-activators for advanced cleaning
  • Backflush valve for quick cleaning
  • Easy to use


  • Backflush needs to be capped when not in use

4. OASE BioSmart Koi Pond Filter up to 5.000, 10.000 Gallons


Worried that your koi pond won’t be cleaned and maintained in the long run? Consider the OASE BioSmart 5000 Pond filter for your water garden. It uses a flow-through filter design with biomechanical filtration systems. It also uses a high-surface-area filter foam and has a sludge drain for easy elimination of rough debris.

An advanced feature you will love is its built-in cleaning indicator which advises you to clean the filter. It also has an all-time water temperature display. It does get the job done, making sure you have crystal clear water with no debris, with minimal maintenance and easy cleaning features. Distinct filter zones are also tactically placed to leave the beneficial bacteria in the pond.

UV clarifiers may work well with the BioSmart 5000 pond filter. It may be beneficial for your pond, yet the BioSmart 5000 works well with its innovative filtration system for maximum oxygenation.


  • Innovative filter design for maximum oxygenation
  • Distinct filter zones
  • High-surface area filter foam
  • Built-in cleaning indicator
  • Water temperature display


  • Gravity-fed outlet

5. TetraPond Submersible Flat Box Filter for Koi Pond up to 500 Gallons


The TetraPond Submersible Flat Box Filter is not your usual koi pond filter which needs digging through your garden. This submersible filter is easy to use and it makes your pond water clear. It also fits a variety of pumps, perfect for your water garden. The filter box can also be opened for the replacement of filters.

It looks compact but it gets the job done in cleaning your water. The filter may be submerged as it draws water in and processes it through a foam mat to remove grime and other particles. The discharged water is already clean and is good for aeration of your koi or pond, through a waterfall or a fountain.

This submersible filter may float, so you need to weigh it down to be fully immersed. Until fully submerged and the air is completely out, it will then hold water and start to work its wonders on your water garden.


  • Submersible water filter
  • Flat box and sleek design
  • Easy to use
  • Fits different pond pumps
  • Easy to replace filters


  • Flat box filter may float and needs to be weighed down

6. CNZ Koi Pond Filter System with UV Sterilizer up to 660 Gallons


The beauty and cleanliness of your pond can only be kept with the right water filter. The CNZ All in One Pond Filter System kills unwanted bacteria and algae with its built-in UV sterilizer. It also has a water fountain feature for a well-designed water discharge scheme, up to three fountain attachments for a variety of displays. Advanced filtration system through a large filter and a bio filter media does ensure that water is thoroughly cleaned. The filter media could also be changed to your preference. Garden landscaping will no longer be a hassle as this pond filter system can be fully submerged.

CNZ All in One Pond Filter System may be heavy when submerged. But the weight is worth the efficiency and pond-filtering power it can provide for your fish pond. This is perfect for smaller pond landscaping with its submersible feature.


  • Submersible water filter
  • Built-in UV sterilizer
  • Water fountain attachments
  • Advanced filtration system
  • Easy to replace filters


  • The unit may be heavy underwater

7. Aquascape Submersible Pond Water Filter up to 400 Gallons


Perfect for your koi pond is the right landscaping design and a quality water filter. The Aquascape Submersible Pond Water Filter has got to be one of the most subtle water filters that clean your pond without being an eyesore.

This submersible filter fits most pumps for a crystal-clear water. One of its unique features is the ceramic filtration rings for good bacteria to colonize. Pump maintenance wouldn’t be much of a hassle as it has a pre-filtration sponge for effective biomechanical filtration. It also has a removable cage with a large surface area that prevents clogging of unwanted dirt and debris. This filter significantly keeps your pond clean, clear, and healthy.

While the pre-filtration sponge is its unique and strong feature, it may be not as fine to filter smaller than usual particles. The great thing is it can be replaced or a finer filter media may be added to ramp up its performance.


  • Submersible water filter
  • Fits most pumps
  • Uses ceramic filtration rings
  • Pre-filtration sponge for biomechanical filtration
  • Removable and easy to clean cage


  • Pre-filtration sponge is coarse

8. Koral Filters PRO Koi Pond Filter Media


Have fewer disappointments on lumpy and flimsy filters by using the Koral Filters PRO Koi Pond Filer Pad Media Roll. With its 1.25 to 1.75 inches thick filter, it surely is thicker with more durable material. It takes pride in having an open fiber construction to let a high volume of water flow through. Having it in a roll also provides you with great convenience as you can cut it to your desired size. This filter pad is also washable and can be used multiple times, making it perfect to filter out fine particles in koi ponds. It is also easy to clean despite filtering all the unwanted gunk and debris.

Filter pads may be prone to wear and tear especially on larger ponds. But the durability and thickness of the material assure you that it can filter out dirt and give your pond crystal clear water.


  • Thick filter
  • Open fiber construction
  • Cut-to-fit roll package
  • Washable
  • Easy to clean


  • Prone to wear and tear

Koi Pond Filter System Buying Guide 

Koi pond filters generally maintain the clarity of the water and the healthy habitat of your koi. These filters are easy to maintain and are a must. As your fish will produce waste on the daily, it is important to have the koi pond filter that does the job in cleaning and maintaining quality water for your koi.

Most ponds have two filters –for the pump and for the pond itself. The pump filter ensures that the water runs smoothly while the main filter for the pond is the one that sieves your pond with the fish waste like nitrite and ammonia. Most of these filters are biomechanical, filtering out the good bacteria and the dirt and debris that accumulate through. Some filters may also have a drainage hose or a backflush system to improve efficiency.

These filters may be submersible inside the pond or maybe external and are just installed in the nearby garden connected through a hose. You need to consider the size of the pond, its capacity, and the number of fishes it will most likely hold. Factors on submersible or external filters must be pondered upon before purchase.

Submersible Water Filters

  • It is installed directly in the pond and is easily disguised.
  • Easy to plumb in your water garden with not much connections.
  • May be difficult to wire for electricity and may expose you to electric shock.
  • They are difficult to access for maintenance as they are submerged.

External Water Filters

  • Easier to clean and maintain as they are externally installed.
  • Intricate connections may be required with more difficult plumbing.
  • Provides you with easier wiring systems and less likely to cause electrical short circuits.
  • These may be hard to disguise as you may need to dig a hole to conceal its body or may need other decorative pieces to blend in your water garden.

What is a Koi Pond Filter?


The filtration system of a koi pond is vital for the overall health of your koi and its habitat. A koi pond filter prevents the nitrogen cycle from getting out of balance in your pond. In this cycle, if ammonia will accumulate, it may be toxic to your koi and other fish.

How do Koi Pond Filters Work?

Fish produce both physical and chemical waste. As they live in the pond, it may be difficult to manually take their waste products out. Koi pond filters may have a mechanical filter that works best by sieving sold wastes from pollen, dead leaves, and from the fish itself. These filters may have multiple stages to filter through different particle sizes. It will filter through coarse particles, then to finer and smaller ones gradually before reaching the biological process.

Biological filtration is also important as unseen wastes such as chemical byproducts cannot be filtered mechanically. This is an aerobic process wherein ammonia is broken down into nitrites and then into nitrates. Filters with the large surface area through ceramic rings or porous rocks is more powerful as it provides an area for beneficial bacteria to thrive through.

After passing through the biomechanical filtration process, the unwanted debris is trapped in the filter and other waste products may be drained through.

Types of Filter for Koi Pond

As koi and water waste products accumulate, your pond will greatly benefit from the right type of filter. Most of the available filters already combine these different mechanisms to provide pond owners a more powerful and efficient way of cleaning and maintaining their ponds.

Some filters are ‘all-in-one’ which has the capacity to filter better than separate filter systems. Filters work by removing unwanted physical or chemical toxins in the pond.

Mechanical Filter – these remove dead leaves and other solid wastes that have been in the pond

Biological Filter – these remove toxins not readily seen, it also retains the good bacteria which contributes to the aeration of your koi pond

UV filters – these alter the composition of the algae in your koi pond and will basically clump up the algae for easier removal and filtration. Different filtration systems can also be observed in different koi ponds. The location and size will matter in installing a specific kind of filtration system for your pond.

Gravity Return Filters – the filter outlet is generally placed at a higher ground than the pond, and these filters are pump-fed. Water simply passes through the filter and returns via gravity, no extra pressure is used.

Pressure Filters – these are used for small to medium ponds wherein water leaving the filter is pressurized, giving you more flexibility as to positioning the filter in relation to the pond.

Gravity Feed Filters – these are more complex systems designed for larger ponds.

Why Do You Need Filter for Koi Pond?

The beauty of your koi lies beyond the perfect landscape and the lovely corals and plants surrounding it. The health of the koi and the water it lives in is essential to keep the elegance it portrays. A water filter significantly reduces and eliminates the toxic waste products from your fish and it keeps the water clean. This brings much clarity and joy to your water ponds, knowing that their habitat is at its best.

Known to be notoriously messy, koi needs tender care and this can be great given with the right filtration system for your pond. For them to grow and bring about their natural colors, they need the perfect environment to thrive in. A filter is an absolute need to achieve the best health conditions of your koi.

Depending on the number of koi you have or the size of the pond your koi lives in, the right filter will help in keeping your koi away from the mess they naturally live through.

As the bioload of your koi increases, the need for a filter will also be great. The right filter will keep your koi healthy and thriving and will maintain the sophistication of your water pond.

Frequently Asked Questions 


How to build a koi pond filter?

Koi pond filters are widely available and can be easily installed near your pond. You can also build your own koi pond filter with a bucket with a thick filter and red lava rocks inside.

  • Select an area where you will place your koi filter
  • Shovel a hole fit for your pond filter just to the top
  • Place the koi filter in the hole
  • Connect the plumbing of the pump and the filter
  • Connect both tubing for water inlet and outlet
  • Finally Connect the pump to power and switch on
  • You may disguise your filter through decorative rocks or plants

How to clean a filter for koi pond?

Modern filters are only cleaned as per manufacturer’s instructions on how they are cleaned. Usually, they are cleaned by either passing through water over the media or by water flow reduction through a pressurized filter. You may rinse the media in a bucket of pond water rather than tap water as it may contain chlorine, which is harmful for the good bacteria. Some koi pond filters have external cleaning pumps to clean their mechanical components. UV clarifiers are generally not cleaned but are replaced from time to time.

How often should I clean my filter for koi pond?

Koi pond filters are cleaned once a week. Mechanical filter pads may be cleaned every one to two weeks or when there is reduced flow. You may also check the bottom of the filter and remove any clumps of algae and other debris.

How to know what size of UV filter for koi pond?

UV filters are sized generally by the speed of water or flow rate it goes through. Know how many gallons of water your koi pond holds and how many gallons are pumped per hour. A rule of thumb is that you may use 10W of UV light per 1000 gallons for UV clarifiers and 30 watts of UV light per 1000 gallons for UV sterilizers.

Where to buy koi pond filter?

Koi pond filters are widely available online. They are also found in home and garden improvement centers, too. Online marketplace, such as Amazon and eBay also have these pond filters.


Koi have been a great addition to every home, office or commercial garden. Being the living jewels that they are, they bring beauty and joy as they charmingly swim though koi ponds. These beauties thrive though the best koi pond filters, the right amount of care and sufficient maintenance. They are symbols of victory and success. Your koi pond could also be embellished with the right plants and flowers that will surely compliment the splendor of your koi. Building your own koi pond could be a great hobby as these graceful koi fishes are surely a feast in the eyes. Buy the best koi pond filters today!

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