Pond Filters: The foundation to clean pond water

Pond filters are foundational for cleaning pond water and maintaining a healthy environment for fish. Understanding types of filtration and the best filter for your pond can take some research. We interviewed our pond techs to lighten your load and provide their top tips in this post. Dive in to learn all about the wonderful world of pond filters.

Do all ponds need a filter?

Do fish ponds need filters?

Pond filters are vital for ponds with fish or other aquatic life. Plain and simple fish make ponds dirty, and you need a way to filter out the muck. Specifically, feeding fish results in fish waste and uneaten food. If left unattended fish waste is not only dirty, but also toxic.

Do ponds without fish need filters?

Pond owners without fish don't HAVE to have a pond filter, but many prefer to have one for water clarity. Filters clean out debris and help achieve that coveted clear pond water.

Types of filtration

There are three ways to filter pond water: mechanically, biologically and chemically. Mechanical and biological filtration are most common, but chemical filtration can help, too.

Mechanical Filtration

Mechanical filtration is the act of physically trapping debris. This is most commonly done with filtration pads.

When using mechanical filtration it's important to clean your pads from time to time to keep them from clogging. We suggest cleaning with your pond water (not hose water). This will sustain any beneficial bacteria that has grown in the filter. However, if you're only interested in using them as straight mechanical filtration, for example pads inside a skimmer, then cleaning with a garden hose is perfectly acceptable.

Biological Filtration

Biological filtration requires media and beneficial bacteria. Filter media is usually anything with surface area that beneficial bacteria can make their home. This includes filter pads, lava rocks, bio-balls, bio-beads and more.

Typically to get beneficial bacteria into a new pond you will need to add some. You can find a plethora of options here. Any biological filter must undergo a period of ‘maturation’ before it is fully efficient. During this period of time, beneficial bacteria will colonize on the filter media until the bacteria population is large enough to purify the waste in the water. The initial maturation of the filter can take up to a month. Some time and patience are naturally required for this growth to occur. 

After bacteria has attached to your media, this form of filtration is very low maintenance. Since they're living organisms, you just let them do their thing. The only manual cleaning required is during winter shut down, and then again when you restart the next season.

Chemical Filtration

While not nearly as common as mechanical and biological filtration, chemical filtration has its place.

Activated carbon is one type of chemical filtration. Use this to absorb water stains from leaves or to remove chemicals. This treatment can be particularly helpful if you overdose your pond or if a neighbor does some spraying that creeps over to your pond. To implement in your pond simply place the activated carbon in a fine mesh media bag inside a skimmer or waterfall box.

Types of Pond Filters

Different types of pond filters serve different needs and preferences. We break them down below.

Submersible In-Pond Filters

Submersible in-pond filters are best suited for smaller sized ponds. Available as all-in-one kits and standalone filters. Standalone filters are plumbed to the suction of a submersible pump, where the pump is pulling from the filter.

These filters are good for light mechanical filtration and light biological filtration. The Oase Filtral and Pondmaster 1000 Pond Filter are both top rated pond filters in this category.

External Pressurized Filters

External Pressurized Filters sit outside a pond. Water is pushed to the filter where it stays pressurized, so it can be used in various setups such as running water back up to a waterfall. You'll find them available with internal foam, bio-media or sometimes both. 

Most models also include an integrated UV Clarifier. Three we recommend include Oase FiltoClear, Aquascape UltraKlean and the EasyPro EcoClear.

Gravity Fed Waterfall Filters

These are primarily open tanks with a spillway, used to start a waterfall. A pump pushes water into the unit via a bulkhead fitting.

Typically a gravity fed waterfall filter will fill from the bottom up. Then when the water hits the spillway it overflows. The spillway starts a nice, even waterfall (which can range anywhere from a few inches to 50 inches wide).

Waterfall filters provide filtration through filter pads and/or media added inside the tank. Most come with pads and a media bag. Bio-balls or other media (to fill the bag) are often sold separately.

Our pond techs like the Aquascape Pond Filter and Waterfall Spillway for small waterfalls. For large waterfalls they point to the EasyPro Pro-Series Aquafalls Filters.

External Gravity Fed Flow Through Filters

These are similar to waterfall filters, but there's no wide spillway. Usually a single pipe discharges water—these models cannot tolerate a high flow.

Inside external gravity fed flow through filters you'll generally find stacked filter pads. The filter itself is placed away from the pond (out of sight) with PVC pipe running from the filter as its return to the pond. These provide mechanical and biological filtration for most any sized pond.

In this category we recommend the Oase BioSmart or Matala BioSteps-II.

Rotary Drum Filters

Rotary drum filters (RDF's) remove micro debris from the pond. A rotating drum inside physically separates the debris. An integrated booster pump pushes to a spray bar to clean the drum screen. These filters are all-stars at filtering out fine sediment.

Our team prefers the Sea Side Aquatics Rotary Drum Filters. Some of these are available with wifi options for hands free cleaning.

Trickle Down Filters (Bakki Showers)

Known as bakki showers, trickle down filters, are a traditional filter often found on ancient koi farms in Japan. Stacked boxes with ceramic media inside hold good bacteria. (Media sold separately.)

Bakki showers are external gravity fed systems that sit above the water level. They provide excellent biological filtration. Some have a small waterfall attachment for a cascade effect. Others just have an open pipe discharge.

Water enters the top of the filter and trickles down through each box. As water flows through and around the media, it becomes infused with oxygen.

We're proud to carry Sea Side Aquatics Bakki Showers—models are available with 4" outlet discharge or waterfall discharge.

External Moving Bed Filters

External moving bed filters are fantastic biological filters. Their large tanks hold plastic bio-media, but what sets these filters apart is aeration. Inside an air diffuser pushes out high volumes of air that keep the media moving. This provides the bacteria on the media with more oxygen—aiding their aerobic processes and making them more efficient.

We recommend the Oase ProfiClear or Sea Side Aquatics Moving Bed in this category.

Best Filters for your pond

Choosing the best filter for your pond, comes down to pond specs and preferences. You'll need a filter that can handle your pond size and fish load, and you'll need the physical space required for your choice. Consider if you want the filter out of sight, or if additional functionality is desired (like a waterfall). Hopefully this post has helped you understand how different pond filters work, so you can make the choice that best aligns with your goals. When it comes to spending money on the pond, spend it on filtration. You can cut corners everywhere else. 

We are always here to assist you along the way. With so many choices, we know it can be overwhelming. Don't hesitate to reach out to our highly trained (and super friendly!) pond techs.

Article Posted: 05/21/2024 09:22:28 AM