5 Ideal Filter Systems for Koi and Small Garden Ponds

New pond-keepers often wonder why they need a filter for their water garden. Natural ponds don’t have a filter, so why does a water garden need one?

Natural bodies of water usually have a source of running water, with either a stream or spring flowing into it. This helps to flush away nutrients and fish waste.

Best Pond Filter Reviews

There is also a natural balance between the level of fish, plants and billions of bacteria that control and recycle waste and maintain a nutrient balance.

The fact is, a man-made koi pond or water garden is not like a natural pond. Your pond is basically a hole in the ground lined with a water-proof plastic layer to keep the water from seeping out. It would never exist unless you built it.

Why do I Need a Pond Filter?

How to choose the right filtration system?

Types of Pond Filters

A Word About UV Clarifiers

We’ve looked at the different types of pond filters suitable for the average backyard pond. All of these filter catagories are available in different sizes, giving you many options to choose from. Here are a few top-rated pond filters to help you make an informed filter selection for your own pond.

Top-rated pond filters list

1. OASE BioSmart 5000

The BioSmart gravity filter system uses multiple stages of mechanical and biological filtration system in a compact external filter box.

The filtration system is designed for medium-sized ponds with a moderate fish population.

The manufacturer rates the filter for ponds up to 5,000 gallons. It is not suitable for a heavily stocked expert koi pond.

Pond water is channeled through a series of filter foams that will culture beneficial bacteria. The filter system also acts a settling chamber. The water flow slows as it passes around the foam pads. Heavy debris falls to the bottom of the filter box. This helps reduce clogging of the filter pads.

The BioSmart system has a special filter cleaning mechanism that squeezes out the foam pads without having to remove them. Just raise and lower the filter pad handle several times. Dirt and debris is flushed away through a separate sludge drain. No need to remove the filter pads, just rinse out the filter box.

The stepped hose barbs accept hoses from 3/4” to 1 ½”. OASE recommends the AquaMax Eco Classic 1900 or AquaMax Eco Premium 2000 pump for this filter. The filter measures 23 x 16.1 x 19.1 inches.


  • 2-inch sludge drain for easy cleaning of the filter box.
  • Built-in foam pad cleaning mechanism.
  • Dial indicates when it is time to clean the foam pads.
  • Solid construction.
  • Easy installation.


  • None.

2. Pond Boss Filter Kit with Pump

The Pond Boss internal pond filter is an easy to use filter for smaller ponds up to 500 gallons.

The water pump sits inside the filter box.

Water is pulled into the filter by the suction of the submerged pump.

Water is filtered through two layers of foam pads.

The first layer is coarse open-cell foam that catches large debris like leaves, plant stems and strands of algae. This protects the smaller pore foam pad from clogging too quickly.

The fine foam pad collects dead algae and smaller particles that cloud the water. The foam pads also protect the pump from clogging.

Plastic “bio balls” are included to provide surface area to aid in growth of beneficial bacteria.

The kit includes an ETL listed, energy efficient 320 GPH fountain pump. The fountain head creates an above-pond spray that is attractive and aerates the pond water.

The diverter valve is used to reduce the flow rate through the fountain head if necessary. The filter measures 12.25 x 6.25 x 7.


  • All-in-one pond filter kit.
  • Easy to set-up, just drop it into the pond.
  • Includes a water pump and fountain head.
  • Diverter valve is handy to reduce the flow rate.
  • 16’ power cord.
  • 1-year warranty.


  • Requires you to pull the filter out of the pond for cleaning.
  • Small filter surface area clogs sooner that wider submersible filters.
  • Fountain spray pattern can be blown by the wind.

3. Pondmaster 190 Pump and Filter with Fountain Head

The Pondmaster 190 pump and filter kit is similar in concept as the Pond Boss kit.

The Pondmaster includes a pump and fountain head but has some notable differences.

The filter system uses a reliable Danner 190 gph magnetic drive utility pump.

Water is drawn into a thick layer of open-cell foam which traps large debris like leaves and stems. A second layer of foam captures fine debris and acts as a home for bacteria, biologically purifying the pond water as it passes through.

The filter pads are larger (12” x 18”), which provides a greater filtration surface. This reduces clogging and allows the filter to run longer before maintenance is required.

The energy efficient water pump draws water through the filter pad then discharges through the bell fountain.

The fountain kit aerates the water and creates a beautiful, wind-resistant water pattern.

The filter measures 8½”x 10½” x 2½”. Rated for ponds up to 400 gallons.


  • Larger filter surface for better filtration.
  • Less clogging.
  • The filter handle makes it easier to remove from the pond.
  • Bell fountain head.
  • 10’ power cord.
  • 5-year warranty.


  • Larger dimensions take up more room in the pond.

4. TotalPond Complete Pond Filter with UV Clarifier

TotalPond’s pond filter is an external pressurized filter design.

The filter has a screw-on sealed lid that keeps the filter under pressure from the pump.

Gravity filters must be placed above the water level. However, the TotalPond filter can be place anywhere, even below the water level due to the pressurization.

Water is pumped from the pond and into the canister. Two layers of foam pads capture debris and will need to be removed periodically for cleaning. Plastic biological filtration balls are included.

This filter comes with an integrated 9-watt ultraviolet (UV) clarifier. The clarifier will kill floating algae cells as they pass by the UV light bulb that is encased in the water-proof housing. This helps keep the water clear without a green tint.

The TotalPond filter is recommended for ponds up to 1200 gallons. The manufacturer states that it can be submerged inside the pond too. However, this would make cleaning the filter difficult. The filter would be very heavy and hard to lift out of the pond.

The filter does not come with a water pump. The recommended pumps include TotalPond pumps: DD11560, DDUV800, LLUV1050, LL1200, LLUV1300, LL2000. The filter dimensions are 17.7” x 13.7” x 9.9”.


  • Economical pressurized pond filter.
  • Black color blends into landscape.
  • Includes a UV clarifier.
  • 16’ power cord for the clarifier.


  • Does not come with a water pump.
  • Requires two electrical outlets for UV and water pump.
  • Uses thin plastic that may not hold up well over time.

5. TetraPond Bio-Active Pressure Filter with UV Clarifier

This German-designed pressurized pond filter includes an ultraviolet clarifier.

Inside the filter Tetra’s plastic “bio-activators” serve as both debris removing and biological filter media.

Pond water flows down through the bio-activators which remove suspended debris and dirt from the water.

The plastic filtration media is unique to the TetraPond filter. The design of the plastic bio-activators provides a large surface area and unrestricted water flow to all the media for improved cleaning.

During normal filtration, the bio-activators capture dirt and debris from the pond. The extensive surface area allows beneficial bacteria to colonize for biological filtration. The filter can be back-flushed to remove dirt.

There are no filter pads to clog or change. During a back-flush, the bio-activators allow water to flush away sludge and debris.

The UV clarifier exposes single-celled algae to ultraviolet light as the pond water is pumped through the clarifier. The algae die and clump together and are removed by the bio-activators inside the pressurized filter.

Tetra Debris Handling Pumps are recommended for this filter.


  • Three sizes are available: 1,500, 2,500 and 4,000-gallon ponds.
  • Has a backflush feature.
  • Does not use foam pads.
  • High-quality construction.
  • Sturdy lid-clamps.
  • Complete instructions.
  • 2-year warranty.


  • More expensive than budget pressurized filter.

Final recommendations

If you have a small pond the Pondmaster 190 is an easy solution for keeping the water clear and aerated. The kit contains everything you need in one package. The high-quality water pump and bell fountain head gives you great value in a ready to use filter system. The filter handle makes it easy to lift the filter out of the pond for servicing.

If you’ve got a larger pond, the OASE BioSmart 5000 Pond Filter offers powerful filtration with easy maintenance. The external filter with the OASE cleaning systems makes maintenance a breeze.

For the most advanced filtration and algae control, the TetraPond Bio-Active Pressure Filter with UV Clarifier is our choice. This filter, coupled with a clog-proof Tetra Debris Handling Pump, will provide crystal clear water, algae control and easy maintenance. The bio-activator media never needs replacing and can be back flushed with a flip of a switch. This top of the line pressure filter is the ideal choice for larger water gardens and koi ponds.

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