There are several types of filtration for your freshwater aquarium. Choosing the right one is essential for a healthy ecosystem! In this article, I'll look at the different options and how to make the best choice.
There are different types of filtration: internal pumps, external pumps, sump systems, air filters, gravel filters, sand filters, and UVC filters. Each aquarium can have its own settings, depending on the overall setup.
The different types of filtration for a freshwater aquarium
If you have a freshwater aquarium, it's important to understand the different types of filtration available to keep your fish and plants happy and healthy. In this section, we'll discuss the most popular types of filtration, ranging from internal and external pumps to UVC filters and more. Each type has its own unique advantages, so let's take a quick look!
Internal Pump
An internal pump is compact and ideal for smaller aquariums. They are easy to install and offer both filtration and water circulation. Although their filtration capacity is limited, these aquarium filters are suitable for use with tanks up to 100 liters.
Hang-on Filter
This filter is especially suitable for small aquascapes where you want to conceal the equipment. The filter hangs from the aquarium and pumps the water back into the tank via a narrow tube and a small waterfall. Although its filtration capacity is limited, it offers a neat solution for smaller aquariums up to 50 liters.
External Pump
External pumps are more powerful and are located outside the aquarium. They are perfect for larger aquariums and provide better filtration and filter material management. Most external pumps consist of several trays that you can fill with suitable material. I personally mainly use filter floss or ceramic media, and if necessary, a filtration material such as HS Algae Control. External pumps are typically used for aquariums ranging from 100 to 400 liters.
Sump
A sump is a glass or plastic tank placed beneath the aquarium. It can accommodate multiple filters, heaters, and other equipment. Water flows into the aquarium via a pipe with an overflow. This is ideal because you have complete control over your filter chamber. It also provides more liters of water, which provides a better buffer. However, it's important to have sufficient space; this type of filtration is recommended for aquariums of 200 liters or more. 
Air filter
Air filters are perfect for shrimp and breeding tanks. They work by blowing air through a sponge, which draws in and filters the water. Shrimp, microbes, and other organisms settle on the sponge, resulting in a culture of beneficial bacteria. These filters are ideal if you want to filter multiple aquariums simultaneously and they also provide air exchange within the aquarium.
Gravel filter and sand filter
Gravel filters are often placed in the bottom or sump of the aquarium. They provide biological filtration by filtering the water through the gravel. A gravel filter is virtually identical to a sand filter.
Sand filters use sand for filtration. This type of filter is very effective at removing small particles from the water, while a gravel filter works much coarser.
UVC filter
UVC filters use ultraviolet light to kill bacteria and algae in aquarium water. This helps keep the water clear and prevents disease. This UV treatment is particularly effective against green algae. This powerful UVC light kills unwanted guests, keeping the water clear. However, keep in mind that they don't filter through the aquarium ecosystem, like a sponge filter does. I've written a separate blog post about this; click here to learn more about how UVC filters combat algae.
The function and advantages and disadvantages of each filter type
Below you will find an overview of the different types of filtration, including their advantages and disadvantages.
| Filter type | Advantages | Disadvantages |
|---|---|---|
| Internal Pump | Compact and easy to use, maintain or replace. | Limited capacity for large aquariums and has little bacterial build-up. |
| External Pump | Efficient for larger tanks and easy to maintain, often also adaptable with internal heating. | Less space-saving, expensive to purchase and requires installation. |
| Sump | Versatile and offers better filtration, completely adaptable to the needs of the aquarium. | Complex installation and maintenance. |
| Air filter | Ideal for multiple aquariums and aquariums with invertebrates. | Limited filtration capacity for larger aquariums. |
| Gravel filter | Good for biological filtration and bacterial culture. | May accumulate dirt over time and requires more effort to start than other filters. |
| Hang-on | Effective for small aquariums and out of sight. | Low filtration capacity and water flow, so not suitable for aquariums with many fish. |
| UVC filter | Keeps the water clear and free of algae. | Increases energy consumption and kills unwanted guests without contributing to the bacterial culture. |
How to upgrade your aquarium filter
Did you start small with an internal filter? That's fine! But don't rule yourself out for an upgrade. If you notice your aquarium is starting to grow or the water isn't as clear as you'd like, it might be time to upgrade to an external filter. This is especially recommended if you have an aquarium with at least 200 liters. And if that's still not enough? Then you can even opt for a biological filter!
Conclusion
It really depends on your aquarium and what you want to achieve. Keep in mind that an over-filtered filter is always better than one that's too small. You can always turn down a filter, but insufficient filtration can lead to algae and disease in your aquarium. Choose wisely and give your fish the best they deserve!
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