Last updated on July 13th, 2023
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Over the years, I have noticed that pond filters have come a long way and maintenance is now much easier than it used to be. We don’t half have it easier now, especially when it comes to cleaning the filters. I remember when box filters were all you could really get. The thing is, they did and still do a great job at cleaning pond water and I think they are one of my favourite types of pond filters as they need cleaning less often if you invest in a decent size filter that is appropriate for the size of your pond.
Basically, they hold a decent amount of mechanical and biological media which is essential for a healthy pond with clear water. Now, I’m no expert but I hope my experience can help some people out when choosing the best pond filter.
However, I’m now a big fan of pressurised pond pumps, such as this Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz with its semi-self-cleaning feature. It’s affordable for what you get too. It really is such as good pond filter for the money but this particular model does not have the built-in UV light that a lot of alternative models come with.
If you don’t have a separate UV Clarifier like me then it’s well worth upgrading to this AllPondSolutions Pressurised Koi Fish Pond Filter with the UV Steriliser. I find that these pressurised pond pumps are great for small and medium-sized ponds. I like that I can place them above ground, buried in the ground, wherever I want or need to. This obvously has its advantages over the box filters that need to be above the pond because they are gravity fed. However, this makes them perfect for waterfalls, although you can just have them above your pond, going straight into your pond.
Even though the design is nothing new, I still think that a good pond filter box such as this Blagdon 9W Minipond 6-Stage Box Filter is still my favourite choice, especially if you keep koi carp.
They are easy to set up and great for using with a waterfall as already mentioned. What I like is that they have plenty of biological and mechanical media, usually have a larger more powerful UV light, and do a great job of filtering water. They’re generally easy to clean too with easy access from the top. The task is usually being a little innovative with hiding them, which is why they are great for incorporating into a waterfall.
Don’t forget about the pump and the maximum pressure
Now, this is really important, you do need to buy the correct pond pump with the correct flow rate to match the filter. The reason this is important is that if the water flows too quickly, the UV light doesn’t have enough time to do its job and causes the free-flowing algae to flocculate. This basically means they stick together becoming large enough for the mechanical filters to catch them.
This is how you get rid of green water caused by algae. If you do have a slightly more powerful pump than recommended, you can always use a pressure reducer to help reduce the pressure from your pump.
Something else I like about a lot of these pond filters is that most (not all) now come with a UV clarifier, as shown in the picture above, which helps prevent and remove green water caused by algae. Something that is probably one of the most common issues I see in ponds. Now, I’ve discussed UV clarifiers here where I talk about why I sometimes recommend having separate UV clarifiers. You can use a more powerful model as the ones built into the filter are sometimes a little underpowered, that being said, most are generally good enough.
Now, there is one type of pond filter I have not mentioned yet, all-in-one pond filters. I like these for small ponds because they include everything. The filter, pump, and UV clarifier are all built into one system. They’re easy to install, literally plug it in, and place it in the pond, and job done. The tradeoff I find is that they need cleaning once a week, or maybe every couple of weeks because the filter space for media is limited. If you have a lot of fish, you may even need to clean it every few days. I like this Hozelock 1760 Easyclear 3000 All in One Pond Filter UVC, it’s a great example and a reliable model that really easy to get set up and going.
Personally, I find that if you get a dedicated pond filter, the biggest size that makes sense is either a box filter or a pressurised filter. Combine this with a decent pump and then maybe add a pond skimmer which I have discussed here if you have a lot of floating leaves. This usually does a decent job at keep the water crystal clear.
Do you really need a pond filter?
For most pond enthusiasts, the answer is most certainly going to be that you need some sort of filter system going on. If you have a fish pool, wildlife pond, or eco pond and you want clear water and like to feed the fish, you are going to need some sort of filtration system for your pond. If you have a pond with plenty of plants and a few fish, then you may get away with not having a filter system. However, if you don’t have enough mechanical filtration, clump algae is going to cause problems.
If you have a larger eco pond with lots of plants, then you will probably get away with just having a waterfall and pond skimmer for the whole pond as a filtration system because it has such a large surface area. For most people, including myself, this is simply not the case.
Dealing with blanket weed – multi-coat
I wanted to bring up blanket weed, this has caused me issues in the past with filter systems. I have noticed that it causes the filter systems to need to be cleaned much more often as well as causing more wear and tear on the filter media reducing the lifespan. I highly recommend using this Cloverleaf BA500 Blanket Answer to help prevent and treat blanket weed. It’s easy to apply, mix the multi-clear power with some water in a bucket until it dissolves, and then mix it in your pond. The pump and filter system will mix it through all the water but if you don’t have a pump, then make sure you mix it well throughout all the water with a net.
Best Pressurised Bio Pond Filter – Self-cleaning
Best Pond Filter Boxes Reviews
1. Blagdon 9W 12000L Minipond 6-Stage Box Filter
The Blagdon 9W 12000L Minipond 6-Stage Box Filter is the most sophisticated pond filter in this review when it comes to the filter system itself. It’s a gravity filter system so the box must be placed higher than the level of the water as it uses gravity to return the clean water to the pond. It’s a simple but effective system that works. It is also a great choice if you want to reduce maintenance and cleaning as it will last around 4 weeks between cleaning.
This 12000 Minipod is suitable for ponds up to 12,000L so it’s quite large, but for me, bigger is better as it just means less cleaning. But bear in mind that this is for a pond that’s over 75cm deep, has no fish, and is in shade. Adding fish or having a shallower pond reduces the volume of water this filter can handle. (See the Buyer’s Guide for more details about these relationships.)
Basically, the size of the pond most filters are recommended for can be as much as half if you have fish and your pond is in the sun. So, a filter of 12,000 litres might only really be suitable for a 6000 litre pond if it has a lot of fish and is in the sun. They also sell smaller and larger models, so you will be able to select the right model that will be better for your pond.
The table below gives you an idea of which filter size you actually need.
One thing that sets this Blagdon series of filters apart is that each model in the range had six stages of filtration. The UV clarifier light (as shown in the picture below) kills green algae, the spray bar oxygenates the water, graded foam traps debris and waste, the Pro bio media creates healthy water, the polymer wool polishes the water and lastly, the chemical foam reduces chemical pollutants. All six filters work one after the other in sequence to produce the cleanest water at the outlet.
The hinged lid on the filter box makes it easy to open to clean the filters, this is something I have found to be not that simple with some filters I have used in the past. I like the safety feature of the micro switch that turns off the UV light if the lid is opened or removed, even if the power is still on. This prevents anyone from looking directly into the UV light and harming their eyes.
You can safely check that the UV light is operating. Just remove the spray bar and hold a piece of plain white paper up to the UVC outlet. You should see a faint blue reflection if the light is on. This may not be visible in daylight though.
This filter comes without a pump. And a downside, though not a deal breaker, is that it also comes without hoses. This is fine as you can choose your own pump or you might already have one anyway. Just make sure it’s the right size pump.
- Black UV pond gravity filter system for medium-sized ponds.
- The filter has a six-stage design.
- For ponds up to 12,000L max (over 75cm deep without fish in shade).
- The hinged lid makes it easy to clean the filters.
- Three hose fitting adaptors: 1.27cm; 1.91cm; and 2.54cm.
- A safety switch to prevent the 9W UVC light from working when the cover is removed.
- The safety rating of IP56 is one of the highest waterproof ratings.
- The hose is not included.
- Comes without the pump.
The Blagdon 9W 12000L Minipond 6-Stage Box Filter uses mechanical, biological, and chemical filters to clean and polish the water flowing through it. I like that the three sizes of hose fittings mean that it fits into most standard pond filtration systems so fitting yours be fairly straightforward.
The Blagdon 9W Minipond 6-Stage Box Filter is my Best Pick in this review of the best Pond Filter Boxes. If not this model, then it would have to be a pressurised bio pond filter, one of which is reviewed below.
2. Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz
Best Pressurised Canister Filter
The Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz is a great alternative to a filter box. It doesn’t come with a pump or a UV clarifier light so you may need a separate UV clarifier, however, most filters don’t come with a pump anyway unless you go down the all-in-one filter route. Its three hose adaptor sizes allow it to fit into most pond filtration systems that already have these other pond appliances installed, so it should be fairly straightforward to install.
This is a pressurised pond filter in a canister-shaped receptacle. This means that you can install it either above or below ground, which is one of the main advantages because it makes it easier to hide. It uses foam filters for mechanical filtration and a SUPRA+ bio media to encourage good bacteria to grow for biological filtration, something which is a must for healthy water. The single clamp on the lid lets you remove it for easy access to the filters for replacing them.
And speaking of cleaning, you can do this automatically which is what I like about a lot of these canister filters. That’s the Powerclenz part of this Fish Mate filter’s name. Just turn a knob on the top of the filter canister from Run to Clean and it runs water through the foam filters to clean them. I especially like that there’s a separate outlet pipe for the sludge generated by this action so that you don’t have to disconnect the water outlet pipe to empty the dirty water. Personally, I would direct this onto flowerbeds or collect it if you have raised beds as it’s great for the soil.
- Green canister pressurised pond filter.
- You can install it above or below ground.
- Automatic cleaning of filters by twisting a knob from RUN to CLEAN.
- Separate sludge outlet for cleaning filters.
- Mechanical and biological filtration.
- SUPRA+ bio media.
- Single clamp ring on the lid for ease of access.
- Intake and outlet extended by 19mm; 25mm; or 32mm hoses.
- Three-year guarantee.
- Leaks a bit
The Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz is a good choice of a pressurised style filter box if you already have everything else you need to clean your pond water (pump; UV clarifier). The three hose adaptor sizes let you fit this to the hoses of most filtration systems. And the automatic cleaning features reduce this chore to the minimum so this is a feature that is very useful, making cleaning and maintenance much easier.
The Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz is my choice for the best pressurised canister filter in this review.
3. AllPondSolutions Small Fish Pond Filter Box Kit
Best Pond Filter Kit To Get Started
The AllPondSolutions Small Fish Pond Filter Box is a full kit. You receive the filter, a pump, and a UVC steriliser. And all the hoses you need are included as well. This is everything you need to clean your pond water, in one purchase. This is a great piece of kit to get you started if you have a small pond and it takes away the complications of matching up the individual parts such as pumps, piping etc.
The pump has a 2,300L flow rate and you know that it works perfectly with the other two pond cleaning appliances. The UV clarifier is a must and this one comes with a 9W bulb. All three pond cleaning units are designed for small ponds, that’s those up to 6,000L with no fish but the unit will be suitable for smaller ponds with fish. (See the Buyer’s Guide for an explanation of how this volume changes with fish or sun).
The filter box has both mechanical and biological filters in it. The mechanical filters are Japanese matting and has both coarse and fine grade filters, while the biological filter is bio balls. It is all pretty standard stuff but good enough to get your water filtered and clean.
Two gauges are in the lid of the filter box. One tells you the temperature with the box and the other is an indicator that the filters are dirty and need cleaning or changing so this is a nice feature that not all filters have. There’s also a viewing window so you can see that the UVC light is working properly.
If you already have a pond filtration system set up, you can buy the AllPondSolutions Small Fish Pond Filter Box with just the filter box here.
- The dark grey filter box kit comes with a filter, pump, UVC steriliser and hoses.
- The pump has a 2,300L/hr flow rate.
- UV steriliser light is 9W.
- Best for small ponds up to 6,000L with no fish.
- Filters are Japanese matting, coarse and fine foam, and bio balls.
- Gauges built into the lid are a thermometer and dirty filter indicator.
- The hose is 3m long.
- Viewing window to check the UVC is working.
- The outlet pipe is too short.
If you’re just setting up a pond filtration system in a small pond, especially as a beginner, the AllPondSolutions Small Fish Pond Filter Box Kit gives you everything you need to start out. There’s a pump, a filter box and a UV steriliser. All three of these components together keep your water clean. And even the hoses are included.
The AllPondSolutions Small Fish Pond Filter Box Kit is my choice of Best Pond Filter Box Kit.
4. AllPondSolutions Pressurised Koi Fish Pond Filter with UV Steriliser
The AllPondSolutions Pressurised Koi Fish Pond Filter with UV Steriliser is for garden ponds with water volumes up to 5,000L and it’s a good alternative to the AllPondSolutions Pressurised Koi Fish Pond Filter with UV Steriliser. Don’t go away if that’s not the size of your pond because this is just one in a whole range of sizes. This model is so available for ponds up to 3,000L; ponds up to 6,000L; and ponds up to 8,000L.
As a pressurised pond filter, this AllPond Solutions model can handle more water than more conventional gravity-fed filters. It sits on the side of your pond where the filters work alongside the UV steriliser/clarifier to clean your pond water.
The UV steriliser light is 11W of power so more powerful than the other models in this review which are 9W. This serves to kill the green algae in the water which clumps together and sometimes drops down to the bottom of the pond. The rest head to the mechanical and biological filters.
The mechanical filters are coarse and fine foams that take out solid debris of various sizes. Then comes the biological filters of bio balls and K2 media. This is where the beneficial bacteria grow that break down the organic pond waste. And then the clean water exits the pond filter box.
You know when it’s time to clean the filters as there’s a float mechanism that raises up when the filters are dirty. And the cleaning task is easy as you just turn a handle on the top of the box. This lets water in to rinse the sponges inside; you don’t have to open the box to do the cleaning. However, some online reviewers report that this cleaning operation has been hit or miss for them. The dirty water from this process exits the filter via a separate outlet to the clean water.
- Black pressurised pond filter that’s compact.
- Has a built-in 11W UV clarifier light.
- Clean by rotating the handle.
- For ponds up to 5,000L.
- Biological and mechanical filters include coarse and fine foams, K2 media and bio-balls.
- The float mechanism lets you know when it’s time to clean the filter.
- The max pump flow rate needed is 5,000L/hr.
- Hose adapters are 20mm, 25mm and 32mm.
- The cable length is 5m.
- Spin cleaning doesn’t always work.
The AllPondSolutions Pressurised Koi Fish Pond Filter with UV Steriliser is a good choice filter and UV light combination for those who already have a pump in their pond system. I like that it comes in various sizes for different ponds and that the hose fittings are in standard sizes.
5. Hozelock 1760 Easyclear 3000 All in One Pond Filter UVC
The Hozelock 1760 Easyclear 3000 All in One Pond Filter UVC is designed for smaller ponds up to 3,000L and it is a good all-in-one solution. An added feature is that, as well as the filter, the pump and the UV clarifier light, it comes with an integrated stem. This lets you add a waterfall or a fountain as a feature for your pond. A waterfall and a fountain are both decorative and serve to keep your pond water aerated with oxygen.
The UV clarifier light is 5W so a little on the weak side. That being said, it will still kill the green algae and causes it to clump up. The foam filters then trap the clumps, or the clumps fall to the bottom of the pond, out of the way.
The Easyclear 3000 pond filter uses foam filters (coarse and fine) as its mechanical filtration to remove pieces of debris and waste. The Kaldness K2 biomedia is used as the place where good bacteria are encouraged to grow to break down organic pond waste.
This pond filter unit is compact and discrete and won’t stand out if you situate it on the pond floor.
If the idea of a waterfall or a fountain along with your filter appeals to you, check out a larger size in this same model. The Hozelock Easyclear 4500 is the same as this model but for ponds up to 4,500L. Both the Hozelock Easyclear 6000 (6,000L) and the Hozelock Easyclear 9000 (9,000L) let you run a fountain and a waterfall at the same time.
- Blue compact pond filter with 5W UVC light and integrated pump.
- For ponds up to 3,000L.
- Built-in pump.
- Foam filters as mechanical filtration and K2 biomedia as biological filtration.
- The integrated stem lets you connect either a fountain or a waterfall.
- Easy to install.
- Two-year guarantee.
If you have a small pond, then the all-in solution of the Hozelock 1760 Easyclear 3000 All in One Pond Filter UVC is for you but they do have larger models for larger ponds too. With the pump, filter and UV clarifier, you have everything you need for clean water in a simple system. An added attraction is that you can attach a waterfall or a fountain to this filter and further oxygenate your clean water. The only real downside is it will need cleaning more than a box filter or pressurised canister filter. The upside is that is easy to install and ready to use in minutes.
My Buyer’s Guide for Pond Filter Boxes
The two main questions to answer before making your purchase choice of a pond filter box are: What size do I need? And what filter types are included?
This Buyer’s Guide helps you come up with the answers.
What size filter do I need?
How big is your pond?
This is not the straightforward question that it seems to be. All filtration units state the volume of water that they can handle, usually as the number of litres. But many have some small print that you must read. Blagdon’s website, for example, has a comprehensive chart spelling out exactly the size and circumstances of the ponds each of their models deals with.
The depth of the pond, whether it sits in sunlight or shade, and the number of fish you have in there all affect the production of green algae and waste which the filtration system is set to clean. The shallower the pond and the more sun and fish, the smaller the volume of water and hence the size of the pond that any given model can handle.
For example, the Blagdon model in this article does clean a 12,000L pond but one that has no fish, is in shade, and is deeper than 75cm. Just add some fish and the volume of water that can be cleaned goes down to 6,000L.
Working out the correct size
Not all manufacturers give this kind of detailed information. It’s worth using any chat facility on the manufacturer’s site to give them your pond details on the above issues and ask them for the size recommendation.
Types of filtration media
Mechanical, biological and UV clarifiers are the main types of filtration media available on the market. Here’s what they all are.
Mechanical filters trap and remove solid waste and debris. These filters are sponges or foam blocks and come in coarse or fine grit. You have both in your filter system.
As the dirty water flows into the filtration system, it first encounters the coarse pads that take out the bigger sediments and stuff, and then the fine pads that take out the smaller bits.
It’s important to regularly clean these filters as they become clogged up with trapped debris.
After passing through the mechanical filters, the cleaner water reaches the biological filters. These rely on the nitrogen cycle and use good bacteria to break down the pond waste. They convert the waste to chemicals (nitrates) that are useful as pond fertiliser.
The key to successful biological filtering is to allow the beneficial bacteria to grow upon the bio-balls or K2 media that’s in your filter. You need as many of these good bacteria as possible so look for filters that have a large surface area of biological filter media for the bacteria to grow on.
And check that you can clean the mechanical filters in the system without touching the biological ones. You don’t want to wash off all the good bacteria along with the debris from the foam filters.
Some pond filters come with a built-in pond clarifier. This is a UV light that kills the green algae in the water. The algae then drop down to the bottom of the pond and remain in the water and are caught by the filters as waste the next time through the filtration system.
A UV clarifier works by passing water around a tube containing a UV light. The light disrupts the DNA of the single-cell algae, killing it. Without this green sludge, your pond water, in time, becomes crystal clear.
If your chosen pond filter doesn’t have a built-in UV clarifier, you can always add a separate one to your pond filtration system. I review pond clarifiers and make my recommendations in 5 Best Pond UV Clarifiers – see the bottom of your pond.
Many online reviewers of electric garden products complain that their purchase arrived without a plug. They don’t realise that UK regulations specify that any appliance for use outdoors in the UK must NOT have a plug attached. This is so you can hardwire it into your outlet box. So remember to go and buy your own plug and (if needed) find someone who can wire it for you.
A pond filter box is a necessity no matter how small or large your garden pond is. Sunlight encourages green algae to grow, fish always produce waste, and who knows what garden matter and debris will find its way into the pond. Keeping your pond water clear and sparkling enhances your enjoyment of the pond and creates an enticing habitat for all manner of wildlife.
Our Best Pick is the Blagdon 9W Minipond 6-Stage Box Filter. This has six levels of filtration including filters that remove chemicals and polish water.
The Runner-up is the Fish Mate 15000 Pressurised Bio Pond Filter with Powerclenz. This is a basic filter without any other pond system components that fit into most existing pond filtration systems.
Aside from the pond filter, you can use a pond skimmer to remove waste from the pond. Oxygenate your pond water with a decorative fountain or a pond aerator. If your pond filter doesn’t have a built-in pump, select the pump separately. And if your pond is really in a bad state, consider a pond vacuum cleaner.
Last update on 2023-11-11 / Affiliate links / Images from Amazon Product Advertising API