Water Garden UV Filters: Which Is Right For You?

Water Garden UV Filters: Which Is Right For You?

We all know that proper filtration is a critical part of maintaining a healthy water garden. This is why water garden UV filters are such a popular option.

Which UltraViolet filter is right for your water garden? The filter that meets the requirements for water volume, durability, functionality, and water flow of your water garden.

Behind every healthy pond is a reliable filter system. Its purpose is to keep the water clear and healthy. Having a UV filter can also prevent any algae problems. This great benefit is certainly convincing more and more water gardeners to purchase their own UV filters.

What is an Ultra Violet Filter and How Does it Work?

Ultra Violet filtration systems vary in complexity and size. It is important that you know what you’re looking for to meet your needs and match your requirements. It is good make sure that you understand how water garden UV filters work before making a purchase.

UV Filters Defined

UV filters are often referred to as UV clarifiers or sterilizers. But, although it is called a “UV filter”, it isn’t actually a filter. What a filter does is to physically get rid of those dead algae clumps from the pond or any other unwanted solid materials. When placed based on your pond size and flow rate, UV filters (or UV classifiers/sterilizers), on the other hand, reduce microscopic organisms and some bacteria that could threaten the life of your fishes. Water garden UV filters also kill free-floating algae.

A UV filter commonly consists of 4 main components – a quartz sleeve, germicidal lamp, ballast, and a casing or housing. The quartz sleeve protects the UV lamp from the water so that it can still be submerged. The ballast is vital in providing for the lamp’s electrical requirement while the casing is where the water flows through and holds all of the components of the device.

How Does Your UV Filter Work?

UV filters work by exposing algae to high levels of UV light and destroying their DNA and killing them efficiently. This results in them clumping together. It clears your pond water from single-cell algae that could affect the health of your water feature.

You will still need a separate pond filtration device along with the UV light to remove those clumps. You can buy the units separately. However, some water garden filters have a built-in UV clarifier. UV filters come with a fluorescent tube that emits UV light. This light kills the algae and forces the algae to clump together. This makes it easier for the filter to remove the clumped algae. By removing the algae you end up with a healthy and clean water garden feature. Not only does it ensure healthy and clean water but also makes an essential element for beautiful aquatic displays.

To ensure that your UV filter works properly, the right amount of water should be pumped through the ultraviolet light. If the water is pumped too fast and the amount of water is too large, the algae won’t have sufficient contact time with the UV light and therefore are not killed. However, if it is too slow, the algae can reproduce faster in the pond than the filter can keep up with.

What Type of Filter Do You Need to Remove Dead Algae?

After your UV filter or UV clarifier is done killing free-floating algae, it is now the job of your filter to get rid of those dead algae clumps. When it comes to the filter types, you have two options – a biological and mechanical filter.

  • A biological filter works by using helpful bacteria to clean water. Instead of removing dead matters from the water, the filter traps them inside a tank that contains beneficial bacteria. Then, the bacteria decompose organic waste materials, leaving your water cleaner and healthier than ever.

This is an appealing option for those who want to keep their pond organic since the essential bacteria are naturally-occurring. Just remember that they need a constant water supply to stay alive, so you have to keep your pump running regularly.

  • A mechanical filter, on the other hand, works by trapping debris and dirt to ensure that your water remains clear and clean. This means that you have to manually remove the waste materials caught in the filter regularly.

Regardless of the type of filter you choose, make sure to have a UV clarifier that comes with it or buy a standalone unit for your water feature. A UV filter significantly makes the filtration system more effective and efficient.

Where to Install the UV Light?

Commonly, the UV light is installed in line with the filter and the pump, regardless of the type of filter. The pump gets the water to the UV clarifier, and then, the filter gets rid of the dead algae.

However, a lot of biological filters that come with build-in UV light. Ensure to place a biological filter before the UV light itself. This is because UV light works better if the water flow is cleaner. While the debris and particles are being filtered out by the device, the UV light penetrates deeper into the water, reaching more algae to kill. Pre-filtering the water before passing it through the UV clarifier ensures higher kill than having it penetrate less clear water.

Additionally, the pump sucks up small rocks that could be transported to the light, causing damage to the quartz sleeve. Therefore, placing the UV light after the filter is beneficial. This helps prevent the possible damage of the quartz sleeve, which is a critical component of your UV clarifier.

Which is the Right Water Garden UV Filter for You?

When it comes to installing a new feature or deciding whether to buy something you don’t know much about, researching is the key. A water garden is already a pretty big investment to have, so it makes sense that everybody wants to get their money’s worth.

For this very reason, we have come up with a list of factors that you need to consider when choosing a UV filter for your water garden. This list goes through the basic details of the what and why they are important to know about. After all, there is nothing worse than purchasing the wrong item and having regrets later down the track.

Water Volume & Size

The type of UV filter you buy should depend on your pond’s size. You should avoid the temptation to grab the first one you see on the shelf. The size of the water feature or pond is determined by the water gallon capacity of the pond. This also refers to the amount of water the pump can move per hour. Often, small ponds range from about 500 to 1000 gallon capacity and the large ones may have a ten-thousand-gallon capacity.

So, you want to pick a UV filter that’s capable of handling your water feature’s gallon capacity. It’s highly recommended that you double the size of the filter for your water feature. This means that if your pond has a 500-gallon capacity, you might want to install a filter that can handle 1000 gallons.

Quality & Durability

Just like with most things, the power of UV filters reduces over time. This can affect the overall performance of your device, especially its ability to remove those ugly green water. Although one easy solution might be to replace it, it is not always the most practical option for every water garden feature. Therefore, it makes a significant difference if you choose a high-quality unit that will last long.


UV filters are essential to stopping the production of algae in your pond. They also ensure the overall cleanliness of the pond water. Although this is the primary function of UV clarifiers, not all pond filtration systems are created the same. Some filters come with UV filters or clarifiers and others don’t.

Often, it is recommended to buy a device that already has a UV filter with it. But, there are also some instances where you only need a UV light. Make sure that you get the right device with the most appropriate functionalities for your needs.

Cleaning Convenience

Is the water garden UV filter simple and easy to clean? Because this is another question that you should ask yourself when searching for one. Eventually, you will need to clean the UV lamp and the UV light casing. Calcium and dirt buildup on the quartz sleeve and this can reduce the device’s overall effectiveness.

Therefore, a thorough but gentle cleaning is important as the quartz tends to be more brittle over time. When looking for a unit, you want a device that allows easy cleaning and maintenance. You will find that an easy-to-clean feature allows you to remove all the stored debris and dirt in their filter without much effort.

Pond & Fish Density

Some owners don’t realize this but the density of your fish and the pond size will affect your filter’s overall performance. You can’t always have the same type of filter if you increase your pond size and fish density. Ideally, your filter size should depend on your fish population and the amount of waste they’re expected to produce. So, you should know the amount of fish a filter can handle before making a purchase.

Also, it would be helpful to know how densely populated your water feature or pond is. Having a lot of plants can help clean your water garden, so you want to consider that too before choosing a water garden filtration system.

Is it Submersible?

You can find a lot of UV filters that allow UV lights to be submerged underwater. However, there are also some devices that should be placed outside the pond. This is mainly dependent on the unit or model. Submersible UV lights are often true to the standalone ones, as they need to be placed in line with the filter and pump. Those that can be installed outside the pond, on the other hand, are commonly the biological filtration systems that just come with UV lights.

Know Which UV Filter is Right for You

There’s nothing worse for any water garden owner to see their pond water turning into green. Therefore, proper care and research are vital to obtaining the right product. Even if you found the most affordable and functional UV filter or clarifier, if it’s not the right unit for your water feature, your efforts will be in vain. There is no one-size-fits-all feature in any model, so you have to do your homework.

Recommended UV Filters for Water Gardens

Manufacturers these days continue to add new or unique features to their water garden filters that attract more water gardeners. This can be both a negative and a positive thing. The negative being that there are more products to choose from and positive that the new features or options are the improved versions.

Some of these offer more functionalities than others, which can greatly enhance their filtering abilities. Unfortunately, these overwhelming options can make it daunting to pick the best one. To help you out, below is a compiled list of some of the UV filters that many people have enjoyed purchasing.

  • TetraPond GreenFree UV Clarifier – This product features a high-efficiency UV bulb that provides eleven months of continuous operation and UV clarifying light to keep water green-free and clean. It is easy to clean and install, and is known to be quite durable. Amazon has it available here.
  • OASE 032218 Filtral 1200 Filter UV with Pump – If you are looking for an all-in-one filter device that comes with four different filter media types, then this might be the right one for you. Though compact, it can provide powerful biological and mechanical cleaning for ponds up to 1200 gallons. Its height can also be adjusted to adapt to different water depths. The flow control technology allows the fountain height and flow rate to be adjusted as well. You can purchase through Amazon here.
  • TotalPond Complete Pond Filter with UV Clarifier – Remove debris and improve water quality in any pond of up to 1200-gallon capacity with this water garden filter. It can be used both inside and out of your pond. Moreover, the addition of a UV clarifier allows more efficient cleaning and purifying your water feature. Available through Amazon here.
  • OXYFUL 36W Non-Submersible UV Sterilizer – This filter’s technology takes advantage of UV lights to eliminate and kill algae, pathogens, and even harmful bacteria from your ecosystem. Its UV bulb is designed to purify your pond, as well as any aquarium. You can install it either horizontally or vertically, but it is best installed after your filter. Available through Amazon here.
  • Jebao CF-10 Pressured Pond Bio Filter – This item boasts of a dual filtration system, providing a healthier and clearer water garden or pond. It can clean water features of up to 1000 gallons. It features a backwash facility and a cleaning indicator for cleaning convenience and comes with a built-in 13-watt UVC. Check it out at Amazon here.

These products found on Amazon are great items for any water gardener, whether you’re a greenie or a hardened veteran. Despite their functionality and capacity, the decision has to come down on what’s best for your specific water garden feature.

Related Questions

This article on water garden UV filters will surely give you the knowledge you would need to know which is right for you. Although this guide contains a lot of information about UV filters and how they work, here are a few more questions that you might find useful.

  • “Is a UV filter necessary?” – If you want to have the clearest water or provide the purist water for your little aquatic creatures, then a UV filter is the solution you seek. Without it, you will have to do more and unnecessary manual work to clean your water garden than you need to.
  • “Is algae really that bad?” – Algae can actually be a good thing. In fact, it is sometimes a part of a good ecosystem. However, too much of it can lead to being bad. So, a filter can help maintain a good balance of algae in your pond. Otherwise, it can be easy for them to get out of hand.
  • “How often should I change the UV filter?– This can vary depending on the unit or model you purchased. You should always read the instructions to find out. Typically, a year is suggested to change the bulb, but if your pond doesn’t contain fish, then you can get away with a year and a half.

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