7 Best 20-Gallon Fish Tank Filter: Keeping Your Aquarium Clean & Healthy

Choosing the right filter for your 20-gallon fish tank is crucial for maintaining a clean, healthy environment for your aquatic pets. A good filter not only keeps the water clear by removing debris and waste but also helps maintain the proper balance of beneficial bacteria, which is essential for a stable ecosystem. With so many options available, it can be challenging to decide which filter is best for your tank. To help you make an informed decision, we’ve reviewed some of the best 20-gallon fish tank filters on the market, considering factors like performance, ease of maintenance, and noise level.

Best Overall: AquaClear 30 Power Filter

The AquaClear 30 Power Filter is widely regarded as one of the best filters for a 20-gallon fish tank. This filter offers superior filtration through a three-stage process that includes mechanical, chemical, and biological filtration. The mechanical stage captures debris and particulate matter, while the activated carbon insert removes impurities and odors. The biological filter, which features AquaClear’s BioMax ceramic rings, provides an ideal environment for beneficial bacteria to thrive, helping maintain a healthy nitrogen cycle.

One of the standout features of the AquaClear 30 is its adjustable flow rate, which allows you to control the water flow to suit your tank’s needs. This is particularly useful for tanks with delicate or slow-moving fish that may not tolerate a strong current. Additionally, the AquaClear 30 is designed for easy maintenance, with a simple media replacement process and a reusable foam filter. Its quiet operation makes it ideal for home and office environments where noise might be a concern.

Best Budget: Tetra Whisper IQ 20 Power Filter

If you’re looking for an affordable yet effective filter, the Tetra Whisper IQ 20 Power Filter is an excellent choice. This filter is specifically designed for aquariums up to 20 gallons and offers reliable performance without breaking the bank. The Whisper IQ 20 uses Tetra’s StayClean technology, which helps maintain crystal-clear water while reducing the buildup of debris and grime.

The Whisper IQ 20 operates quietly thanks to its sound shield and motor design, which minimizes noise to less than 20 decibels—about as quiet as a whisper. This makes it an excellent option for tanks in bedrooms or other quiet spaces. The filter also features an adjustable intake that allows you to control the flow rate, making it suitable for a variety of fish species. The cartridges are easy to replace, making maintenance a breeze, and the bio-scrubber provides added biological filtration to keep your aquarium water healthy.

Best Hang-On-Back (HOB): Marineland Penguin 100 Bio-Wheel Power Filter

Hang-on-back (HOB) filters are a popular choice for 20-gallon tanks due to their ease of use and effective filtration. The Marineland Penguin 100 Bio-Wheel Power Filter stands out in this category because of its innovative Bio-Wheel technology, which provides superior biological filtration. The Bio-Wheel supports a large surface area for beneficial bacteria to colonize, ensuring a stable environment for your fish by maintaining the nitrogen cycle.

This filter also includes a multi-stage filtration system with mechanical and chemical filtration provided by the Rite-Size cartridge. The flow rate is adjustable, allowing you to customize it according to the needs of your aquarium inhabitants. The Penguin 100 is easy to install, operate, and maintain, and its compact design fits neatly behind most 20-gallon tanks. Its robust build and efficient filtration make it a top choice for both novice and experienced aquarists.

Best Canister Filter: Fluval 107 Performance Canister Filter

Canister filters are known for their powerful filtration capabilities and are ideal for tanks that require superior water quality. The Fluval 107 Performance Canister Filter is an excellent option for a 20-gallon tank, offering multi-stage filtration with a focus on efficiency and customization. This filter is compact yet powerful, providing mechanical, chemical, and biological filtration in a single unit.

One of the advantages of the Fluval 107 is its customizable media trays, allowing you to choose the best filtration media for your specific needs. The filter comes with Fluval’s high-quality foam pads, activated carbon, and Bio-Foam, which help to maintain water clarity and promote a healthy bacterial colony. The 107 model is designed for quiet operation, with an efficient motor that minimizes noise and energy consumption. It’s also easy to set up and maintain, with a self-priming feature that simplifies the initial installation and water changes.

Best Internal Filter: Aqueon QuietFlow Internal Power Filter

If you prefer an internal filter, the Aqueon QuietFlow Internal Power Filter is an excellent choice for a 20-gallon tank. This filter is fully submersible, making it ideal for aquariums without a lid or those with limited space behind the tank. The QuietFlow is designed for easy installation with suction cups that secure it to the tank wall.

The Aqueon QuietFlow offers three-stage filtration: mechanical, chemical, and biological. The dense foam cartridge traps debris, the activated carbon removes toxins and odors, and the bio-holster promotes beneficial bacterial growth. The filter also features an adjustable flow rate, allowing you to customize the water movement to suit your tank’s inhabitants. Despite its compact size, the QuietFlow provides efficient filtration while operating quietly, making it perfect for smaller tanks or low-profile aquariums.

Best Sponge Filter: Hygger Aquarium Double Sponge Filter

For those who keep delicate fish or fry, a sponge filter is often the best option. The Hygger Aquarium Double Sponge Filter is a top-rated choice for 20-gallon tanks, offering gentle filtration that won’t harm small or sensitive fish. This filter uses two high-density sponges to capture debris and waste, providing mechanical filtration while also fostering the growth of beneficial bacteria.

The Hygger sponge filter is air-driven, meaning it requires an air pump to operate, but this also makes it highly customizable in terms of water flow. The dual sponge design ensures maximum surface area for biological filtration, which is crucial for maintaining a healthy aquarium environment. The filter is easy to clean and maintain; simply rinse the sponges in aquarium water during routine tank maintenance to avoid killing beneficial bacteria. Its quiet operation and gentle flow make it ideal for breeding tanks, shrimp tanks, and tanks with small or delicate fish.

Best Undergravel Filter: Lee’s Premium Undergravel Filter

Undergravel filters are an excellent option for those who want a hidden filtration system that also promotes a natural aesthetic. Lee’s Premium Undergravel Filter is a reliable choice for a 20-gallon tank, providing biological filtration through a bed of gravel. The filter works by drawing water through the gravel substrate, where beneficial bacteria can break down waste products.

This filter is easy to install and works well with both air pumps and powerheads to ensure proper water circulation. While undergravel filters are less common today, they remain an effective choice for aquarists looking for a low-maintenance, unobtrusive filtration system. Lee’s Premium Undergravel Filter is durable, easy to set up, and can be used with various substrates, making it a versatile choice for any 20-gallon aquarium.

Choosing The Best 20-Gallon Fish Tank Filter

Choosing the right filter for your 20-gallon fish tank is essential for maintaining a healthy, thriving aquatic environment. Each of the filters reviewed here offers unique benefits, from the powerful multi-stage filtration of the AquaClear 30 Power Filter to the budget-friendly Tetra Whisper IQ 20 and the gentle, air-driven Hygger Sponge Filter. Whether you’re looking for a hang-on-back, canister, internal, sponge, or undergravel filter, there’s an option that fits your needs and preferences.

When selecting a filter, consider your tank’s specific requirements, including the type of fish you keep, the amount of water flow needed, and how much maintenance you’re willing to perform. Remember, the best filter for your 20-gallon aquarium is one that provides efficient filtration, is easy to maintain, and suits the needs of your fish and overall setup. With the right filter, you can ensure a clean, healthy, and vibrant home for your aquatic pets.