Choosing the right filtration system is crucial for the success of your small aquarium. Filtration ensures that your tank remains clean, your water quality stays high, and your fish thrive. In smaller tanks, the filtration system becomes even more important because water quality can degrade quickly due to the limited volume. This guide will explore the best filtration systems for aquariums under 20 gallons, covering different filter types, their features, and key considerations to help you make an informed decision for your small tank setup.
1. Importance of Filtration in Small Aquariums
In small aquariums, maintaining stable water quality is vital for the health of your fish. Small tanks have less water, which means waste, uneaten food, and debris can accumulate faster. Without a proper filtration system, toxic compounds such as ammonia, nitrites, and nitrates can build up quickly, stressing your fish and potentially causing disease.
The filtration system helps remove harmful substances from the water, keeping it clear, clean, and free of toxins. It also helps to oxygenate the water, providing a healthy environment for fish to thrive. The best filtration systems for small aquariums should offer efficient cleaning while being quiet, compact, and energy-efficient.
2. Types of Filtration Systems for Small Aquariums
There are several types of filtration systems available for small aquariums. The choice of filter depends on the tank’s size, the type of fish you keep, and the overall tank setup. Let’s explore the most common types of filters for small tanks:
1. Hang-On-Back (HOB) Filters
Hang-On-Back (HOB) filters are a popular choice for small aquariums. These filters are easy to install and offer excellent filtration efficiency for tanks ranging from 5 to 20 gallons. As the name suggests, HOB filters hang on the back of the tank and draw water through a filter media, which traps debris and harmful particles before returning clean water to the tank.
Advantages:
- Easy to install and maintain.
- Provides both mechanical and biological filtration.
- Quiet operation.
- Available in different flow rates, making them suitable for a wide range of tank sizes.
Disadvantages:
- Can be bulky and may take up space around the tank.
- Some models may be too powerful for very small tanks.
Best For: Tanks between 5 to 20 gallons, particularly for freshwater setups with small fish.
2. Internal Filters
Internal filters are placed inside the aquarium, typically at the back or corner of the tank. These filters are ideal for tanks with limited space where an external filter might be too large or intrusive. They draw water into the filter, pass it through filter media, and then return it to the tank.
Advantages:
- Compact and efficient.
- Good for tanks where space around the tank is limited.
- Some models offer both mechanical and chemical filtration.
- Quiet operation.
Disadvantages:
- Can take up swimming space in the tank.
- May require more maintenance if the filter media gets clogged.
Best For: Small tanks (under 10 gallons), or tanks with delicate fish species that need a gentle flow.
3. Sponge Filters
Sponge filters are powered by an air pump and are one of the gentlest filtration options available. They are an excellent choice for very small tanks or for delicate fish species that cannot handle strong currents. Sponge filters provide mechanical and biological filtration by trapping debris in the sponge while also promoting the growth of beneficial bacteria.
Advantages:
- Provides gentle filtration, ideal for fry or sensitive species.
- Low power consumption, very energy-efficient.
- Easy to maintain and clean.
- No risk of sucking up small fish or plants.
Disadvantages:
- Limited filtration capacity compared to other filter types.
- Less effective in larger tanks or tanks with heavy waste production.
Best For: Nano tanks, fry tanks, and tanks with very sensitive fish species like shrimp or small bettas.
4. Canister Filters
While canister filters are typically used in larger aquariums, there are models available that can be used in small tanks. Canister filters are external filters that sit outside the tank and draw water into a canister where it passes through various types of filter media, including mechanical, biological, and chemical filters.
Advantages:
- Highly efficient and powerful filtration.
- Offers customizable filtration media options.
- Quiet operation.
- Great for tanks with a heavy bio-load or multiple fish.
Disadvantages:
- More expensive than other filter types.
- Takes up more space outside the tank.
- Requires more maintenance than HOB or internal filters.
Best For: Larger small aquariums (20 gallons and above) or tanks with a heavy bio-load, such as tanks with many fish or live plants.
5. Undergravel Filters
Undergravel filters are placed beneath the substrate (gravel or sand) and work by drawing water through the substrate, providing mechanical and biological filtration. They are not as popular as other filter types but can be a good option for small tanks that have a fine gravel or sand substrate.
Advantages:
- Provides natural filtration by utilizing the substrate as a filter bed.
- Can help promote healthy plant growth by oxygenating the substrate.
- Low-maintenance once installed.
Disadvantages:
- Not as effective for removing visible debris as other filter types.
- Not ideal for tanks with large fish or tanks that generate a lot of waste.
Best For: Planted tanks or tanks with small fish and low to moderate bio-load.
3. Key Considerations When Choosing a Filter
When choosing the best filtration system for your small aquarium, several factors should be taken into account:
1. Tank Size and Capacity
Ensure the filter you choose is suitable for the size of your tank. Some filters may be rated for larger tanks than yours, which may result in excessive water flow. Alternatively, a filter rated for a smaller tank may not adequately clean the water in a larger aquarium.
2. Filtration Type
Different filters provide different types of filtration: mechanical, chemical, and biological. Mechanical filtration removes debris and particles from the water, while biological filtration provides a surface for beneficial bacteria to grow, breaking down harmful substances like ammonia and nitrites. Some filters also provide chemical filtration, which removes toxins and impurities from the water.
3. Flow Rate
The flow rate refers to how much water the filter can process in a given period. For small tanks, you want a filter that provides gentle water movement to avoid stressing the fish. Choose a filter with an adjustable flow rate if possible, especially if you’re keeping delicate or slow-moving fish.
4. Noise Levels
Some filters, particularly powerful ones like canister filters or HOB filters, can generate noise. While most modern filters are designed to be relatively quiet, it’s still important to consider how much noise a filter produces, especially if your tank is placed in a bedroom or office.
5. Maintenance Requirements
All filters require regular maintenance to keep them running efficiently. Internal and sponge filters are easier to maintain, while canister filters may require more attention. Consider how much time you’re willing to invest in cleaning and maintaining your filter.
4. Best Filtration Systems for Specific Tank Types
Here are some recommendations based on common tank types:
- For Nano Tanks: A sponge filter is ideal for very small tanks (less than 5 gallons) as it provides gentle filtration and doesn’t disturb the water too much. You can also use a small internal filter if space permits.
- For 5-10 Gallon Tanks: A Hang-On-Back filter is a great option for tanks in this range. It provides efficient filtration and is easy to install. Look for a filter with an adjustable flow rate to cater to different types of fish.
- For 10-20 Gallon Tanks: A Canister filter or an upgraded HOB filter is perfect for tanks in this size range, especially if you have a community tank with multiple species of fish. These filters offer powerful filtration and can handle more waste.
5. Conclusion
Choosing the best filtration system for your small aquarium is essential for maintaining water quality and ensuring the health of your fish. By understanding the different filter types, key features, and the needs of your tank, you can find the right filter for your setup. Whether you choose a hang-on-back filter, internal filter, sponge filter, or canister filter, ensuring the proper filtration will help create a thriving aquatic environment for your fish.
