A koi pond can be a beautiful and relaxing addition to your backyard. Of course, you need to keep the water clean for the fish to survive. This means adding the best koi pond filter to your other accessories. These units get rid of the waste, bacteria, and other debris for the healthiest environment possible for your fish to live in.
There are several different filter models on the market to choose from. We’ve reviewed five options, with the The Pond Guy AllClear G2-3500 coming out on top. It is great for ponds up to 3500 gallons, has a flow rate of 2,650 gallons per hour, and features three-stage filtration. This pressure filter is fully assembled, easy to install, and has a decent price for added convenience. There are also a few others in our reviews for different pond sizes if needed.
When choosing a new filter, there are a few features to look at. One is the pond size, so you know the filter can handle the amount of water and fish in there. There are few different filtration systems, each of which covers a different cleaning aspect, so check these out as well. The size of the outlet matters since these affect the flow rate of the water. The unit’s dimensions tell you how much space it takes up and the warranty covers you for any issues with the filter. To help you choose the best koi pond filter, we’ve created a comparison table with in-depth reviews and a buying guide at the end to cover every feature.
More features: backflush, 2,650 GPH pump
The guys over at The Pond Guy are a niche company, so they know their stuff. The Pond Guy AllClear G2 is a residential-sized pond filter that provides mechanical and biological filtration as well as UV sanitization for the ultimate pond water quality.
We purchased The Pond Guy’s AllClear G2 pond filter for its full (a bit expensive) price and installed it in a friend’s pond that hasn’t been clear for two years. He had been trying to make natural plant filtration work, but his 4,000-gallon pond was too much for them. In 3 days, this small pump had the water crystal clear.
The effectiveness of the AllClear G2 extends for years, thanks to a proprietary 3-stage filtration system. It uses filter media for both mechanical and biological filtration, while a small UV filtration canister deals with the final sanitization stage.
The G2 is very easy to install, use, and maintain. We didn’t dig a hole as advised since it wasn’t a permanent set-up, but we connected the inlet/outlet hoses easily. After a week of operation, we went ahead to backflush the filter to get all the accumulated gunk out. Overall, we loved The Pond Guy’s AllClear G2 pressurized filtration canister and would recommend it without a second thought.
More features: Top valve mount, Aqua UV tubular media, pre-seeded with natural bacteria
The Aqua Ultraviolet Ultima II 1000 Filter is a compact model that is perfect for koi ponds or aquariums that range from 500 to 1000 gallons. As well as being small, it can also be mostly buried, so it won’t disrupt the aesthetics of your pond. It pumps 500-1200 gallons per hour, depending on the size of your pond, cleaning it quickly to keep your fish in the best environment possible.
This unit has one of the best filter media for a koi pond. It uses this brand’s patented Ultima II filter series, which combines the benefits of both mechanical and biological filtration in a small unit. It has an extremely high biofilm surface, which encourages beneficial bacteria growth without suffocating those healthy microbes.
The mechanical filter uses a thick bed of ridged media, which traps any of the solids that pass through the filter, preventing clumping so the water can flow freely without releasing those solids back into the pond.
Another reason to try out this koi pond filter is the simple backwashing process. It uses a cyclonic method, which requires you to simply rotate a valve to activate the internal jets inside the filter. This separates those collected waste materials from the media and shoots them out through the waste line. This process only takes a few minutes each week or so, depending on the cleanliness of your water, so it shouldn’t be too disruptive to your schedule.
Even the best pond filter for koi can have its issues, which is why you need a decent warranty to cover it in case those issues keep it from working at its optimal level. This one is covered for three years, so any repairs or replacements won’t cost you a thing during that time.
Of course, a filter is more than just its warranty, which the Aquascape 95053 UltraKlean has proven. This unit has a unique sponge-free design, which reduces maintenance while giving you the most efficient filtration possible.
The UltraKlean has three filtration stages. The mechanical filtration uses a water inlet diffuser, which evenly distributes the debris, reducing clumps. There are UltraKlean BioBalls inside that help trap the dirt and debris, plus helps with the biological filtration for producing beneficial bacteria.
A UV clarifier is the third stage of this filtration system. It eliminates the single-celled algae that turn the water in your koi pond green. This uses a UV light, which can burn out if used too much. To prevent this, there is a bulb-saver feature that allows you to set the UV to turn on at specific times.
Another great feature is the cleaning indicator light, which notifies you when the filter needs to be backwashed. This process is quite easy, using the valve to redirect the water and stir up the media inside. This flushes out the debris in only minutes, so it won’t take up a great deal of your time.
More features: Backwash facility, cleaning indicator and a UVC viewing window
If you’re on a budget, you likely can’t afford to spend hundreds of dollars on a koi pond filter. The Jebao CF-10 Pressured Pond Bio Filter is a good solution, costing less than a hundred dollars while still keeping your koi pond clean and your fish healthy.
This filter system uses 3 stages of filtration to clear out everything that doesn’t belong in your koi pond. The mechanical filtration also has three stages of its own, including coarse, medium-coarse, and fine filtration. There are specific foam sponges used for each one to remove different sizes of debris from the water.
The biological filtration uses bio-balls, which encourage the growth of healthy bacteria that can fertilize the aquatic plants in your pond and create a healthy environment for your fish.
The third stage is the UV filtration, which uses a low-voltage UV light. As the water passes through this filter, the UV light kills any algae in it before it is sent through the output and back into your pond.
Cleaning this unit is easy, using the integrated backflushing system. This takes only a few minutes every week or two, depending on the condition of your water. The material used for this unit is thin plastic, so you do need to be a bit gentle with it. Keeping it out of direct sunlight helps maintain the plastic’s integrity. It is also recommended to place it in a hole to secure its position next to your koi pond.
More features: Innovative Flow-Through filter design, built-in cleaning indicator, water temperature display
If you have a large pond that is need of a decent filtration system, the OASE BioSmart 10000 Pond Filter may have the best koi pond filter design to meet your needs. This unit is rather large, so it may be hard to disguise with other pond features, but it is capable of cleaning a pond up to 2500 gallons for a koi pond or a 10,000-gallon pond without fish.
The BioSmart uses a unique flow-through design, which uses both biological and mechanical filtration systems to clean the water and provide the maximum oxygenation possible. It includes filter foams with a high surface area that offer excellent biological filtration. There are distinct filter zones to help promote the growth of beneficial bacteria, which helps maintain the proper nitrogen cycle for reducing harmful ammonia in the pond.
There are also some handy features included for easy use. The first is a built-in cleaning indicator, which tells you when to clean the filter. This process is simple since you don’t even have to take out the filter foams or manually unclog them. You can also open the sludge drain to easily remove any coarse debris.
Another unique feature is the water temperature display, so you always know the exact temperature of the water in the pond. You can pair this with a pond pump and UV clarifier as well, though they are not included with the filter system.
Koi will spend their entire lives in the pond you build for them. This includes eating, sleeping, and using the figurative toilet. They also create a lot of waste, which then needs to be cleaned out of the pond for them to live comfortably. This means getting the best koi pond filter system to clean out the debris, waste, and reduce harmful bacteria that could create an unhealthy environment for your koi.
When looking for a new koi pond filter, you’ll likely notice a list of features that you may not be familiar with. The following sections will help you learn what each of these features is and why they are important for your new filter system.
When looking at the pond size recommended by the pond filter you’re considering, there are a few factors you need to add. An empty pond will stay cleaner than a pond with fish in it, so the recommended pond size varies for these two instances. For instance, the OASE BioSmart 10000 Pond Filter has a recommended pond size of 5000 to 10000 gallons, though only 2500 gallons for a pond that contains koi. If the listed pond size is vaguer, you should double the size of the filter for the pond. For instance, the Aquascape 95053 UltraKlean has a recommended size of 2000 gallons, so it should be used on a 1000 gallon pond that contains a decent amount of koi. You also need to take into account the amount of fish.
A larger fish population requires a larger pond filter to keep up with the waste produced.
There are two main filtration stages for koi pond filters. The first is the mechanical filtration, which removes the solid waste and other debris from the water that flows through the unit. This filter system may include different types of foam filters to catch varying sizes of debris.
There is also biological filtration included in the best koi pond filters. These capture bacteria, such as ammonia, and help it detoxify and become beneficial bacteria that actually improve the environment of your koi pond.
Some units also include UV filtration, which isn’t the same as the other filtration types. UV filtration uses a UV bulb that destroys the DNA of the free-flowing algae in the water, killing the algae. This causes the damaged algae to clump together, making it easier to remove from the pond.
The outlet size on the pond filter affects the flow rate of the water as it passes through the unit. The flow rate determines how quickly the pond is cleaned, so this is quite important. To choose tubing for the pump and any water features, you need the proper outlet size to move every drop of water through the filter each hour. The larger the outlet, the larger the tube size you can use, so the stronger the pump can be to push the water through at the optimal level.
The dimensions of the unit determine how much space it will take up next to your koi pond. A larger unit, like the OASE BioSmart 10000 Pond Filter, will be difficult to hide with decorative features around your pond. This can be a bit unsightly, though necessary for a clean koi pond. Some units can be hidden by burying them almost entirely next to your pond.
It’s best to check out the warranty of a pond filter before you buy one to ensure it covers any issue you may discover when you set up the filter and start it up. The longer the unit is covered, the more time you have to work out those kinks. Some warranties are only for a year or two but a few options, like the Aquascape 95053 UltraKlean, have a full 3-year warranty, so you can try out the unit to make sure it works as expected.
There are a few extra features you may want to check out before buying a new koi pond filter system. One is the materials used to make the unit. All the products we’ve reviewed are made of plastic, so likely can’t be used year-round. This also means they may not be as durable as some other materials, so be careful with your filter.
Cleaning is another thing to look at. The easier it is, the more enjoyment you’ll get out of your koi pond. A backflush option is best since it cleans the unit itself rather than you taking it apart to clean it. This also only takes a few minutes, which is much less time than manually cleaning it out.
When choosing the right pump for your koi pond filter, you need to look at the size of the koi pond. The unit should filter all the water in the pond every hour, so the pump needs to be able to cover this. For instance, if you’re pond holds 5000 gallons of water, the pump needs to have a flow rate of at least 5000 gallons per hour. Though a non-pressurized filter won’t interfere with this, a pressurized one will reduce the flow rate as the water goes through it. If the pump is too strong, it can damage the pressurized filter, so check out the filter’s pump requirements before hooking one up.
Setting up a koi pond filter system is easier than you may think. The following tips will get you started:
The price of your new koi pond filter may be a deciding factor on whether or not you buy it. Many of the products in our koi pond filter reviews are a few hundred dollars, which can be a bit pricey for those on a budget. There are a few that are budget-friendly, though, such as the Jebao CF-10 Pressured Pond Bio Filter. These units still have most of the features found on the more expensive models, though they may skimp a bit here and there. This doesn’t mean they won’t still do the same job, though. They are still fine filters, keeping your koi pond clean and your fish happy.
There are several koi pond filters on the market, so it may be hard to choose the right one to meet the needs of your favorite fish. We do have a few favorites that we think deserve a second look.
Our top choice and the best koi pond filter is the Pond Guy AllClear G2-3500. This pressure filter can handle up to a 3500-gallon pond, and has a 2650 GPH flow rate. It is very easy to install, use, and maintain, and includes a backflush system for fast cleaning.
The Aqua Ultraviolet Ultima II 1000 Filter is best for smaller koi ponds due to its compact size. It uses both mechanical and biological filters and comes pre-seeded with natural bacteria for healthy growth. The cyclonic backwash method cleans it in only minutes.
The Aquascape 95053 UltraKlean uses three-stage filtration, with a sponge-free design that reduces maintenance time. It also includes a bulb-saver timer for the UV clarifier and has a cleaning indicator light to tell you exactly when to clean the unit.