Best Aquarium Filters & Pumps — Up to 20 Litre (2026)
1 aquarium filters & pumps matching capacity “Up to 20 Litre”, hand-picked from UK Amazon listings.
Not sure which one to pick? Read our How to Care for & Maintain Your Aquarium Filters & Pumps guide.
These aquarium filters and pumps are ideal for smaller freshwater setups, specifically designed to cater to aquariums up to a 20-litre capacity. Maintaining a healthy environment for your small fish or invertebrates requires effective filtration – these units provide the necessary flow rate and biological filtration to keep water clean and oxygenated. Many models include adjustable flow rates allowing you to fine-tune the water circulation to suit your specific tank inhabitants, ensuring optimal conditions for their wellbeing.
#1 Pick
NICREW Fish Tank Filter, Internal Aquarium Filter for Small Tank, Coldwater or Tropical Aquariums, Up to 20L, Black- Up to 20 Litre
£11.89
Pros
- Detachable spray bar doubles as a wave maker or surface oxygenator
- Five suction cups keep it firmly in place, mountable horizontally or vertically
- Budget-friendly option that is still one of the best-reviewed small filters on Amazon UK
Cons
- Only suited to smaller tanks up to 20 litres
FAQ
What kind of fish are suitable for a 20 litre aquarium?+
Small freshwater species like Neon Tetras, White Cloud Mountain Minnows, and Corydoras Catfish thrive in aquariums up to 20 litres. It’s crucial to research the specific needs of any fish before introducing them to ensure compatibility and adequate space.
How often should I clean a filter for a 20 litre tank?+
Regular maintenance is key; cleaning frequency depends on bioload, but typically you'll want to partially clean your filter media every 1-2 weeks. Over-cleaning can disrupt beneficial bacteria colonies.
What type of filter media do I need for a 20 litre aquarium?+
A combination of mechanical, biological, and chemical filtration media is recommended. This could include activated carbon to remove impurities, ceramic rings for biological filtration, and sponges for trapping debris.
Are these pumps quiet?+
Pump noise levels vary between models; check the product specifications for decibel (dB) ratings before purchasing. Look for pumps specifically designed for aquariums to minimise vibration and noise.
Do I need an air stone with this filter?+
An air stone is highly recommended to increase oxygen levels in your small aquarium, especially important for densely stocked tanks. This will support the health of your fish and promote healthy respiration.
How do I connect the pump to the tubing?+
Most pumps feature quick-connect fittings or adapters that easily attach to standard aquarium tubing. Ensure a secure connection to prevent leaks and maintain proper water flow.
What size tubing is typically used with these filters?+
Standard aquarium tubing, usually 4mm inner diameter, is commonly used with these pumps. Check the manufacturer's instructions for specific tubing recommendations.
Can I use this filter with a heated aquarium?+
Yes, you can use this filter in conjunction with a heater as long as the heater’s power cord doesn’t interfere with the pump’s operation and water circulation is maintained.
What if the pump stops working?+
Refer to the manufacturer's warranty for details on repair or replacement options. Amazon’s standard returns policy applies, allowing you to return the product within 30 days of receipt for a refund (subject to conditions).
Are these filters suitable for saltwater aquariums?+
While possible, these pumps are primarily designed for freshwater setups. Saltwater tanks require more robust filtration and circulation due to increased salinity and biological demands; consider models specifically designed for marine environments.