Top Tetra Pond Filter Systems
1) TetraPond Submersible Flat Box Filter
- SUBMERSIBLE FILTER: Flat box filter prevents pump from clogging and keeps pond water clear and clean.
- PARTS INCLUDED: Coarse and fine foam pads, tubing and three hose fittings.
- CONVENIENT: Attach to various pump inlets – easy to detach for cleaning.
Tetra Ponds’ entry-level filter is the submersible Flat Box model which is designed as an affordable filtration system in small garden ponds. The filter is very reasonably priced, and contains 2 layers of high quality mechanical sponge media within the main chamber next to the in-take. Water flows from your pond pump and into the main chamber where it passes through a course sponge and then a finer sponge, which work to collect a wide range of debris, from smaller dirt particles to decaying leaves. The media is quite densely packed, and there is little room for additional media or chemical media, but the basic 2 layers provide decent mechanical filtration in most situations.
Due to the small size of this filter box, no dedicated bio-media is included and the mechanical sponges will double as biological filtration and mechanical filtration. Beneficial bacteria will happily colonize any surface where there is ample oxygen and water flow, but the surface should also be optimized to house the maximum amount of bacteria for better filtration potential. Without dedicated bio-media, we feel this filter would be unsuitable for ponds with fish as it just can’t provide the required biological filtration to deal with the large amounts of ammonia produced from fish and feeding.
However, the filter is a great choice for ponds without koi or goldfish, or for ponds with a very small number of guppies or mosquito fish. It’s especially suited for wildlife ponds where the majority of the ponds bio-load comes from leaves, twigs, debris, and natural critters. The filter would also be a useful additional to a larger pond as a pre-filter to a pond pump or main filter system. A pre-filter is essentially a smaller filter that goes before larger equipment and helps catch debris that may clog or reduce the performance of the main systems.
In terms of pump requirements, this small filter will work with a water flow rate of 500-2000 GPH, although we personally would stick with a maximum of 1,000 GPH to prevent leakage. It has been designed to be added to a fountain or waterfall on the out-take, and Tetra Pond actually provides the full filter/fountain kit to remove the hassle of sourcing an ideal pump.
Cleaning can be a bit of a nuisance due to the filter’s submersed nature, which means you’ll have to manually pull the filter out from the pond floor to clean. This is a messy job, and can be even more problematic if you suffer with lots of debris which easily clogs the filter cage. If you suffer with lots of fallen leaves and debris, we advise an external filter for easier maintenance!
Overall, a decent entry-level filter option for wildlife ponds, water gardens, or very lightly stocked nano fish ponds up to 500 gallons. Very affordable, easy to set-up, and comes with a 1 year warranty as standard for peace of mind. If you don’t mind keeping up with the cleaning, it’s a budget-friendly choice.
- Pressurized: No
- Pond sizes: Suitable for ponds up to 500 Gallons (no Fish)
- Type of filtration: Biological and mechanical (dual-purpose sponge)
- Pond Pump: 500-2000 GPH (not included)
- UVC Strength: N/A
- Outlet Size: Fits 1/2″- 1” tubing
- Dimensions: 12.4 x 10.3 x 4.7 inches
- Warranty: 1 Year
- Tetra Pond Flat Box Replacement Filter Pads: link
2) TetraPond Clear Choice Biofilter
- Easy out-of-pond accessibility and simple maintenance
- Mechanical pre-filter sponges remove suspended debris to improve water clarity
- Bio Ring media provide massive surface areas for beneficial aerobic bacteria
Tetra Pond’s mid-range filtration system designed for ponds up to 1,200 gallons without fish, or 500 gallons with fish. This non-pressurized external filter box has both dedicated mechanical media as well as biological media within the main chamber, making it suitable for lighter fish stocks.
A pump is attached to the main intake on the bottom of the box and water flows through 2 layers of mechanical media which work to filter out larger debris and organic matter. Afterwards, the water flows down into the bottom chamber which contains highly optimized ring-shaped bio-media designed to house beneficial bacteria. The way the filter has been designed means the flow is constantly stirring up the layers of bio-media (“moving bed”), providing the bacteria living on the surface with plenty of oxygen, nutrients, and helping to remove decaying debris which can clog them. This design ensures the beneficial bacteria are working optimally, and also means that less cleaning is required on your part – which is always a plus!
As an additional benefit, the in-take line where water enters the filter is fitted with a venturi style system which works to pull more oxygen from the atmosphere into the water. This, coupled with the trickle flow design of water over the filter media, means that beneficial bacteria have optimal conditions for growth.
In terms of maintenance, cleaning is much easier in comparison to the submerged flat box filter. The top of this external filter is removed and mechanical media is accessed directly from the opening. Depending on your debris levels, mechanical media may need cleaning every week or two, which requires the mechanical media to be removed and rinsed with a garden hose to clear debris. Biological media should rarely need cleaning unless it becomes fully clogged with debris, but this should not happen here due to the active ‘moving bed’ design.
You’ll need a pond pump to get things moving, and a pump between 350-550 GPH is recommended for optimal filtration. As this filter is non-pressurized, you’ll need to be careful not to connect a pump which is stronger than this as it’ll cause leaks from the top of the box as water pressure builds. The hose fittings are standard 1/2″ to 1″ ID, and the intake has an interchangeable fittings to suit your hose size, which is a nice touch.
Although not designed for heavy stocked ponds or extra large ponds, this filter would be a good choice for small koi or goldfish ponds up to 500 US gallons maximum. If your pond is larger than this, we recommend either Tetra Ponds’ Bio-active models or a different filtration system. It can also be used in large wildlife ponds above 1,000 US gallons as an upgrade to the much smaller Flat Box Submersible filter. No UV clarifier option is included in this filter, so one would need to be purchased separately if you have algae problems, which will inflate costs.
Overall, a well designed filter system with very good biological filtration potential at a fairly reasonable price point. The model is non-pressurized so would need to sit at ground level, but would make a great addition to smaller fish ponds or larger wildlife ponds where smaller submersible models are unsuitable.
- Pressurized: No
- Pond sizes: Suitable for ponds up to 500 Gallons (with fish)
- Type of filtration: Biological (rings) and mechanical (sponge)
- Pond Pump: 350-550 GPH (not included)
- UVC Strength: N/A
- Outlet Size: Fits 1/2“- 1” tubing
- Dimensions: 15.2 x 15.2 x 11.8 inches
- Tetra Pond Filter Manual:
- Warranty: 1 Year
- Tetra Pond ClearChoice Filter Manual: link
- Tetra Pond Replacement Filter Pads: link
3)TetraPond Bio-Active Pressure Filter
- MECHANICAL FILTRATION: Pond water flows down through the bio-activators, which remove suspended debris and dirt from the water
- BIOLOGICAL FILTRATION: Maximized surface area on the bio-activators allow beneficial bacteria to colonize and attack harmful pollutants in...
- EASY TO CLEAN: The easy backflush valve makes the cleaning process highly efficient
Tetra Pond’s high-end filtration system offering, being able to provide efficient water filtration to fish ponds up to 2,000 gallons. The Bio-active range of filters come in 3 different capacities, ranging from the 1500 gallons, 2500 gallons, and 4500 gallons. These values represent the maximum amount of pond water the filter can efficiently work with when no fish are included in the pond. If you have a large amount of goldfish or koi carp, you will need to half these values when choosing a filter model – for example, if you have a 2,000 gallon koi pond, you would need the 4500 Bio-active model for efficient filtration.
In terms of filtration, the bio-active range have a large amount of optimized bio-media (similar to K1 media) in a central chamber which has been designed for maximum beneficial bacteria colonization. The filter has a “moving bed” design, which means the media is constantly moving inside the filter box, providing extra oxygen and nutrients to aerobic bacteria living on the surface. These filters have obviously been designed with biological filtration mind, and all features tend to point towards improving the efficiency of bacteria within the media – which is great for keeping harmful substances in check!
Sadly, a drawback of these filters is that there is no dedicated mechanical media included, not even as a pre-filter on the intake. The bio-media effectively doubles as mechanical media, which can be a problem if you suffer with a lot of debris or nuisance algae. Debris will become stuck on the bio-media and will require regularly cleaning with the filters back flush function, or the bacteria living on the surface will begin to suffer as oxygen content is reduced. For most ponds, this shouldn’t be an issue, but if your pond is located close to trees, shrubs, or bushes, you should take this into account and either install a pre-filter, or be prepared for more regular cleaning.
When it comes to cleaning, luckily Tetra has made the task incredibly simply with it’s semi-automatic back-flush cleaning system. When it’s time to clean (you’ll know when flow is reduced), simply switch the filter to “pond” mode and position the back-flush valve into a drain, then begin turning the handle to activate the cleaning system. This creates a whirlpool effect inside the main filter chamber, removing debris stuck to bio-media and flushing it out from the back-flush valve into your garden or drain. Here is a video showing the back-flush in action:
Since the filter is pressurized, it can be installed above or below the water line, making it a good choice if you want to bury the box next to the pond in an excavated hole. A UV clarifier is also included with the model pictured here, so the filter will be able to remove green algae articles during the filtration process for better water clarity. Tetra recommends a minimum pump flow rate of 2,500 GPH and a maximum of 4,500 GPH for optimal filtration and to prevent damage.
Overall, a very good choice of pressurized filter with a handy black-flush cleaning system for easy maintenance. The biological filtration is great, and the UV clarifier helps deal with nuisance algae if you have green water problems. A very good all-round choice for koi and goldfish ponds!
- Pressurized: Yes
- Pond sizes: Suitable for ponds of 1500 gallons, 2500 gallons, or 4000 gallons (3 models)
- Type of filtration: Biological and mechanical (Dual-purpose media)
- Pond Pump: 2500-4500 GPH (not included)
- UVC Strength: 9- 18 Watt
- Outlet Size: Fits 1″ – 1 1/2″ tubing
- Dimensions: 17 x 15.4 x 18 inches
- Tetra Pond Filter Manual:
- Warranty: 3 Years
- Tetra Pond Bio-Active Filter Manual: link
- Tetra Pond Bio-Active Replacement Parts: link
How Does A Tetra Pond Filter System Work? (What To Expect)
1) Mechanical Water Filtration (All Models)
All of Tetra Pond’s filter products include some form of mechanical filter media, which is the media primarily responsible for the removal of organic debris. Mechanical media often comes in the form of sponges which vary in porosity, from fine (small holes) to course (larger holes). More layers of mechanical media will allow for greater debris removal, with finer media removing small dirt particles and larger media catching everything from leaves to twigs.
Tetra Pond’s Flat Box submersible filter includes two basic mechanical sponge pads for both course and fine debris removal, sitting in the chamber directly in-line with the intake. Tetra Pond’s Clear Choice bio filter also includes a sheet of mechanical media which works to remove debris before water is passed to a large chamber of bio-media rings. Their Bio-active pressurized filter only includes a single media type which provides both mechanical and biological filtration. In most cases, we prefer to see separate media for better filtration, but this pressurized model has handy systems in place to make the single media choice extremely viable, easy to clean, and quite efficient compared to regular models (explained later).
2) Biological Water Filtration (All Models)
Alongside mechanical media, you also have the equally (if not more) important biological media which will house the millions of beneficial bacteria ready to break down waste substances. Just like mechanical media, you’ll find some form of biological media in all of Tetra Pond’s filters. Beneficial bacteria will colonize any and all surfaces inside a filter which have an ample supply of water flow and oxygen, but they’re best suited for dedicated media optimized for maximum surface area. In TetraPond’s Bio-active and Clear Choice filters you’ll find highly optimized K1-style bio-media, and in the smaller Flat Box model, the mechanical sponge media will simply double as biological media. If you have fish in your pond, you will want specialized biological media optimized for maximum surface area, but for wildlife ponds without fish, dual purpose media can also work fine.
3) UV Sterilization (Bio-Active Model) & Chemical Filtration (N/A)
Finally, another form of media you may want to consider is chemical media, which includes things like activated carbon (charcoal) and zeolite. Unlike mechanical and biological media, chemical media does not always come as standard in filters, and is instead something you add manually to maximize water quality. None of Tetra Pond’s filters come with chemical media as standard, but the Bio-Active and Clear Choice filters have enough room to add chemical media if you need it, which may be useful to take into account.
Likewise, if you have problems with green water (algae) or just want to reduce harmful fee-swimming bacteria and pathogens, having a UV clarifier inside your filter makes sense. Not all filters come coupled with a UV clarifier option, so if you’re looking for algae removal on top of filtration, only Tetrapond’s Bio-Active products meet this criteria. If you’d prefer a different model, you can also always just add a UV Clarifier unit separately on a different circuit to the filter, which should have the same results!
Things to Consider When Choosing a Tetra Pond Filter:
Tetra Pond currently offer three different types of filter systems, and the choice of which model will depend largely on your fish stocks, pond size, and waste levels. Below we have provided some considerations to take into account when choosing a pond filter, with a focus on Tetrapond’s products in particular:
1) Fish Stocks & Bio-Load Requirements
The most important aspect to consider when purchasing a filtration system – can the filter actually handle my ponds bio-load?
Although many things contribute to bio-load (waste), the largest factor by far is the type of fish and the number of fish you keep in your pond. Goldfish have lower bio-load requirements in comparison to koi carp, but if you have a very large number of goldfish, their total waste production could be similar. Most filter systems will give you an idea of what they’re capable of handling in terms of fish stocks, with only Tetra Pond’s Bio-active and Clear Choice models being suitable for any type of fish, in our opinion. Their flat box model is far too small for effective waste breakdown, and will not be able to house enough beneficial bacteria to filter out harmful substances that fish constantly produce. For a wildlife pond, it would be a great choice, but if you keep goldfish or koi, you’ll need to choose a bigger model!
2) Pressurized vs Non-pressurized Models
Another thing to take into account which can have an impact on where you can actually place the filter is whether or not the system is pressurized. Having a pressurized filter just means the inside chamber is sealed, and water moves more slowly through the filtration process, which also allows for more flexible placement. Pressurized filters can be placed above or below the ponds’ water line, which makes them a popular choice if you want to hide the filter by burying the box inside a hole next to your pond. Regular filter boxes are not pressurized, which means they need to be placed at ground height and cannot be buried below the water line as this will cause issues with filtration. Pressurized filters also allow for more densely packed filter media and will filter out debris more effectively in comparison to standard boxes. However, if your pond pump is too weak for a pressurised model, water flow and oxygen may be insufficient for beneficial bacteria to survive, so you need to ensure your pump meets the filter specification requirements. Tetrapond’s Bio-active filter is the only pressurized model they currently offer, with its Flat Box and Clear Choice being non-pressurized products.
3) UV Clarification – Do you have Algae?
If you suffer with green water problems and nuisance algae growth, choosing a filter with a UV clarifier option is a no brainier. Clarifiers work by destroying algae particles at the cellular level using powerful ultra violet light. Water passes through the main UV chamber from your water pump which kills the algae particles, which then become caught in your filter media and are removed when cleaning. The benefit of having a UV clarifier coupled with a filter is that it takes up less space, and often costs much less in comparison to buying the two products separately. As well as this, the UV light emitted will also destroy harmful bacteria, viruses, and pathogens that can make fish sick, so it’s a good choice for heavily stocked koi or goldfish ponds. If you’re selecting a Tetra Pond filter, only their pressurised Bio-Active model comes with a UV clarifier unit included as standard.
4) Pump Flow, Cleaning, & Budget Considerations
Finally, you’ll also want to take into account the filter systems pump requirements, cleaning requirements, and your maximum potential budget. Pressurized filters, such as the Tetra Pond Bio-active, require stronger pond pumps in comparison to a non-pressurized filter of the same capacity, which may mean higher overall purchase costs. However, pressurized models are generally much easier to clean, as they often come with convenient semi-automatic ‘back flush’ functions, whereas a regular filter needs you to manually open the box to get to the media. If you have a pond without fish, the Tetra Pond Flat Box filter is an extremely cheap option, which also includes an optionally water pump designed for the best filtration. This would make selecting a pump much easier, but if your pond is much larger or heavier in fish stocks, you’ll likely have to invest in a separate pump to match the larger filters requirements, such as with the Bio-active and Clear Choice models.
Optimizing & Cleaning Tetra Pond Filter Systems
All of the Tetra Pond filters are fairly easy to clean, with the pressurized Bio-active model being particularly easy due to its automatic back flush feature which actively spins media inside the box and ejects debris through an out-take pipe. The Flat Box model and Clear Choice models both need to be manually opened for cleaning, but the process is not very difficult or time consuming. You can further optimize your water filtration and reduce the amount of cleaning required through various methods, such as installing pond netting, skimmer boxes, vacuuming sludge, and supplementing with extra beneficial bacteria. On top of this, you should also ensure you’re cleaning your filter media correctly so you don’t damage beneficial bacteria or the media itself.
Are Tetra Filters Good Enough For Koi Carp?
Koi are large fish, and have equally large bio-load requirements. Not all filter systems will be suitable for heavy stocked koi ponds, and the same goes for some of the Tetra Pond filter models. Their small Flat Box Submersible filter is totally unsuitable for any amount of koi, and their Clear Choice Biological filter is only suitable for lightly stocked (2-4 fish) koi ponds up to 500 gallons. If you have a pond larger than this, or more koi, you’ll need to look into their Bio-active pressurized models. These filters have better filtration capacity, and should be suitable for garden ponds up to 4,000 gallons, or ponds up to 2,000 gallons with koi.
If you have a fish pond above 2,000 gallons in volume, or a smaller, but very heavy stocked koi pond, you can check out our much larger koi filter recommendations here! These filters have been chosen based on their filtration efficiency, ease of maintenance, and durability. Tetra Pond filters are a great choice for smaller koi or goldfish ponds, but may not be ideal for heavy fish stocks or koi ponds larger than 2,000 gallons.
Tetra Pond Filter Replacement Parts – Where to Buy Them?
If you already have an older Tetra Pond filter, or maybe you’d just like to stock up on some extra parts for peace of mind, Tetra offers a wide range of replacement filter pads, bio-media, hose, and UV bulbs at reasonable prices. We’ve listed some of the replacement parts below for each model from sellers on Amazon to make things easier to find:
What is the best add on filtration system for a decorative pond/waterfall that is concrete and stone. I need it for clarity, reduce algae build up and small debris. My underwater pump is sufficient Nd is hard piped (pvc). Your thoughts.