Koi ponds have an aesthetic appeal and are associated with style and elegance. To maintain the best ecosystem for your Koi fish, you will need a pond filter. The koi fish have a weaker immune system than traditional fish, and so you need to be specific about the choice – the standard pond filter will apparently not do. We highlight our pick for the top best koi pond filter below.

What is it about Koi Ponds that’s got everyone talking?

Having a Koi pond is as trendy as it gets today. Any real estate agent may let you on a secret or two, and they will tell you that Koi ponds increase the market value of the property. Koi pond owners may also tell you how much relaxed they feel watching the koi fish move about in the pond.

Nature has its own healing powers, and the koi are the best indication of that. The ponds have a sense of spirituality and calmness associated with them. Your doctor may notice a positive change if you spend some of your free time watching the fish move about.

And what about the mosquitoes and other insects associated with stagnant water and gardens? Yes! This may be among your worries, but the koi fish will solve this problem for you – something about dessert!

best koi pond filter

Why Should I have a Koi Pond Filter?

For starters, a koi pond filter is heavy-duty and provides the best ecosystem for koi fish. The filter keeps the water clear so you can enjoy every moment of watching the fish swim. What would be the use of having s pond full of koi but can’t see them?

Koi fish are weaker, so they need protection from biological threats. The best Koi pond filter eliminates all biological threats and makes sure that the koi are in a clean environment. A filter will also remove other gunk and junk from the water.

There is something pleasant about a clean environment. When you visit your koi pond and see the crystal clear water, you are sure to be filled with pride and a sense of accomplishment. It is almost as if the fish and the clear water have a calming effect on your soul. Your friends will also love visiting you and your pond to marvel at everything so bright and refreshing.

What to Consider when Buying a Koi Filter

best koi pond filter

Filter capacity

The filter you choose must be appropriate for the fish load and the volume of water in the pond. The filter succeeds in turning the water completely after every few hours. If the amount of water and fish load are significant, then you will be better off with a powerful filter. The thing about koi fish is that they secrete a lot of solid waste and ammonia compared to the other fish and so they need potent filters – the conventional filters will not cut.

The type of filtration

Basically, there are three types of filtration systems: biological, mechanical, and chemical. The biological type is the most important but is not sufficiently able to deal with organic debris coming from outside the pond, such as leaves and grass from the lawnmower – this is where the mechanical system comes in. Ideally, you should have both systems in your koi pond for an effective cleanup exercise. However, many koi filters in the market incorporate both systems – go for them.

UV Sterilization

A filter with a UV sterilizer keeps the water very clean by dealing with the algae effectively. This feature is an excellent addition to your koi pond filter, and you should make sure it is there.

Type of Feed

The water can get back to the pond from the filter through pressure or gravity. Pressure filters use force to push the water back into the pond. This means that they can mainly work from anywhere – even some distance away from the pond but will need a hose for this. Gravity filters use the force of gravity to take the water back. They are usually slightly above the water level and do not need a hose to carry the water back.

Internal/ External

You will find submersible filters on the market, but they are not quite common. They work underwater and are not so easy to maintain. However, the external pond filters are easily accessible and easy to maintain. Filters need cleaning, and those above ground make it easy to do so.

A Review of the Best Koi Pond Filters

OASE BioSmart 5000 Pond Filter Rating

If you have an average fish load or a mid-sized pond, then this pond filter may be the best. It employs both biological and mechanical systems to make sure that your pond has crystal-clear water. Even though it is a compact filter, it passes water through several filter foams to achieve its objective. This process transforms harmful ammonia and nitrates into products useful to water plants. It has a decent maximum koi pond size of 1250 Gal. However, you will need to purchase the UV light feature as an add-on – it is not part of the package.


  • An indicator for sludge drain
  • Compact size
  • A filter option that is user-friendly
  • An internal cleaning mechanism
  • Comes with a temperature gauge


  • You will need to source your connections
  • The outage may be a little inefficient
  • The accompanying instructions are not the best

TetraPond Bio-Active Pressure Filter with UV Clarifier

You cannot take chances where koi fish are involved. You will need the best koi pond filter to ensure that the fish are both healthy and the pond is clean for most of the time. This filter has bio-activators that provide a good surface area for unrestricted flow of water for the efficient cleaning process.

It utilizes both mechanical and biological filtration processes. Its bio-active media converts ammonia and other harmful nitrates into something safe which will help the water plants grow. The filter has its UV light that kills single cell algae. The neutralized algae then settle at a section of the filter where you can later flush it away.


  • Comes with a UV clarifier
  • An extensive surface area for more effective cleaning
  • Bio-active media that converts nitrates
  • Has UV light


  • Does not come with its own pump
  • You will also need an additional filter for the flush port.

Goplus Pond Pressure Bio Filter 4000GAL W/ 13W UV Sterilizer Light 10000L Koi

This filter has almost everything necessary to keep your koi pond healthy and crystal clear. It has efficient pressure filters and a UV purifier to keep the pond clear and hospitable for the koi – this is the primary goal. With this pond filter, you will not need to use harmful chemicals such as algaecide that might kill the koi fish. The filter is easy to use and will only not follow simple instructions.

However, this filter will require a separate submersible pump.


  • This product is easy to install
  • It is also easy to use
  • Easy to remove the top for maintenance
  • Comes with a one-year warranty
  • Kills the algae keeping the water clean
  • It clears the algae within a short time


  • The attached instructions may not be sufficiently clear
  • The filter can clog up

Grech CPF-2500 Pond Bio Pressure Filter UVC 13-watt

This pond filter has both biological and mechanical filters for effective pond cleaning. It is easy to maintain as it comes with an easy-to-operate handle system. The device deals with ammonia and other harmful nitrates by supporting the growth of anaerobic bacteria that converts it. And unlike some models in the market using gravity, this pond filter can comfortably deal with higher water flows. It also has a UV unit that ensures the destruction of bacteria. You will not need to worry about leaving it in the rain as the device is waterproof.


  • Easy to maintain
  • Supports anaerobic bacteria to deal with nitrates and ammonia
  • Can deal with higher water flows
  • Compact design
  • Has a UV sterilizer to deal with the algae


  • The device may clog and the filter media may collapse with time
  • May also have leaking problems with time

OASE Filtral UVC 700 Pond Pump and Filter

If your koi pond is small and your fish load is low, then this product may be the most fitting for you. It has a holding capacity of up to 700 gallons without fish – pretty lightweight. The pond filter is submersible, and so your children or any other person may not tamper with it. This filter uses UV light to eliminate all the algae making sure that it is crystal clear. However, just like any other submersible filter, this product is not so easy to clean and maintain.


  • A very compact size
  • Comes with a UV clarifier
  • Pocket friendly
  • Easy to use – you don’t do much
  • Submersible and outsight
  • The filter works well where small ponds are concerned


  • Has a relatively low flow-rate
  • Only suitable for small ponds


Once you have decided to have a koi pond, you must ensure to provide the best conditions for the fish to thrive. This means having the best koi pond filter. You will not go wrong with any of the filters above, but the TetraPond Bio-Active Pressure Filter with UV Clarifier is best in our opinion for a koi pond.

The filter converts the harmful nitrates into something useful to the plants – this is where the useful microorganisms stay. It also has a UV light to kill off the algae and maintain the cleanliness of the water. This product is also not so hard to install, you can do it on your own.

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