Aquarium Filtration Pumps: How to Choose the Right Filter for Your Fish Tank

A clean, healthy aquarium does not happen by accident. The filtration pump is the heart of your fish tank - it keeps the water clear, removes harmful waste, and creates the stable environment your fish need to thrive. Without the right filter, even the most beautiful aquarium can quickly become a dangerous place for your fish.

At Pet Shopee Australia, we know that choosing the right aquarium filtration pump can feel overwhelming with so many options available. In this guide, we break down everything you need to know to make the right choice for your tank and your fish.

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Why Aquarium Filtration Is So Important

Fish produce waste constantly. This waste breaks down into ammonia, which is highly toxic even in very small amounts. Without filtration, ammonia builds up rapidly and can kill your fish within days. A good filtration pump removes this waste and converts it into less harmful substances through a process called the nitrogen cycle.

Beyond just removing waste, aquarium filters also oxygenate the water through surface agitation, remove physical debris like uneaten food, and help maintain stable water chemistry. In short, a filtration pump is not optional - it is essential for any healthy aquarium.

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The 3 Types of Aquarium Filtration Explained

Before choosing a filter, it helps to understand the three types of filtration that every good aquarium pump should provide.

🔵 1. Mechanical Filtration

This is the physical removal of solid particles from the water. Sponges, foam pads, and filter floss trap debris like fish waste, uneaten food, and plant matter before they can break down and pollute the water.

• Keeps water clear and free of visible particles
• Must be cleaned regularly to prevent clogging
• Rinse in old tank water, never tap water, to preserve good bacteria

🟢 2. Biological Filtration

This is the most critical type of filtration. Beneficial bacteria colonise your filter media and convert toxic ammonia into nitrite, then into the much less harmful nitrate. This process is called the nitrogen cycle and is what makes an aquarium safe for fish.

• Takes 4 to 6 weeks to fully establish in a new tank
• Bio media includes ceramic rings, bio balls, and sintered glass
• Never replace all bio media at once or you will restart the cycle

🟡 3. Chemical Filtration

Chemical filtration uses activated carbon or other special media to remove dissolved impurities, odours, discolouration, and certain toxins from the water. It is especially useful after using medications or if your tank water has a yellow tint from driftwood.

• Activated carbon should be replaced every 3 to 4 weeks
• Remove carbon when treating fish with medication
• Not always necessary in a well-maintained tank

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Types of Aquarium Filtration Pumps

There are several different styles of aquarium filters available in Australia. Each has its own strengths, and the best choice depends on your tank size, fish type, and budget.

🐠 1. Internal Filter

Internal filters sit inside the tank, usually attached to the glass with suction cups. They are compact, affordable, and easy to use - perfect for beginners and smaller tanks.

• Best for: Tanks up to 100 litres, beginner setups, betta tanks
• Pros: Cheap, easy to install, adjustable flow rate
• Cons: Takes up space inside the tank, limited capacity

🐟 2. External Canister Filter

Canister filters sit outside the tank and connect via intake and outlet hoses. They offer the highest filtration capacity and are the preferred choice for larger, heavily stocked, or planted tanks.

• Best for: Tanks over 100 litres, planted tanks, cichlid tanks
• Pros: Powerful, large media capacity, quiet operation
• Cons: More expensive, requires more setup time

🪸 3. Hang-On-Back (HOB) Filter

HOB filters hang on the back rim of the tank with an intake tube going into the water. They are popular in Australia for medium-sized tanks and offer a good balance of performance and price.

• Best for: Tanks between 60 and 200 litres
• Pros: Easy to maintain, good water flow, visible operation
• Cons: Can be noisy if water level drops, not ideal for very large tanks

🫧 4. Sponge Filter

Sponge filters use an air pump to draw water through a foam sponge. They provide gentle filtration and are especially popular for breeding tanks, fry tanks, and shrimp setups.

• Best for: Breeding tanks, shrimp tanks, hospital tanks, nano tanks
• Pros: Very gentle flow, excellent biological filtration, cheap
• Cons: Requires separate air pump, limited mechanical filtration

🪨 5. Undergravel Filter

Undergravel filters sit beneath the gravel substrate and draw water down through the gravel using an air pump or powerhead. They are an older design but still used in some basic setups.

• Best for: Simple fish-only tanks, goldfish tanks
• Pros: Hidden from view, cheap, promotes biological filtration
• Cons: Difficult to clean, not suitable for planted tanks or sand substrate

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How to Choose the Right Aquarium Filter for Your Tank

📐 1. Match the Filter to Your Tank Size

Every filter is rated by the volume of water it can process per hour (litres per hour or LPH). The general rule is your filter should turn over your tank volume at least 4 to 6 times per hour.

• 60L tank - choose a filter rated at 240 to 360 LPH minimum
• 100L tank - choose a filter rated at 400 to 600 LPH minimum
• 200L tank - choose a filter rated at 800 to 1200 LPH minimum
• When in doubt, always go bigger - over-filtration is rarely a problem

🐡 2. Consider Your Fish Species

• Goldfish: Heavy waste producers - need powerful filtration, at least 8x turnover
• Bettas: Prefer gentle flow - use an internal filter with adjustable flow or a sponge filter
• Cichlids: Large, messy fish - external canister filters are strongly recommended
• Shrimp: Sensitive to strong flow - sponge filters are ideal
• Community fish: A quality HOB or internal filter works well for most setups

🌿 3. Planted Tanks vs Fish-Only Tanks

• Planted tanks benefit from canister filters with spray bar outlets to distribute CO2 evenly
• Fish-only tanks can use any filter type suited to the tank volume
• Avoid undergravel filters in planted tanks - they disturb roots
• Sand substrate requires filters that pull from mid-water, not the bottom

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How to Maintain Your Aquarium Filtration Pump

Even the best filter will stop working properly if it is not maintained regularly. Here is how to keep your aquarium pump running at its best.

🧽 1. Rinse Mechanical Media Monthly

• Remove sponges and foam pads and rinse in a bucket of old aquarium water
• Never rinse filter media under tap water - chlorine kills beneficial bacteria
• Replace sponges when they fall apart, not just when they look dirty

🦠 2. Protect Your Biological Media

• Never replace all bio media at once - stagger replacements over several weeks
• Only rinse bio media lightly to remove debris - do not scrub it
• When adding new bio media, run it alongside old media for at least 4 weeks

⚙️ 3. Check the Pump Impeller

• The impeller is the spinning component that creates water flow
• Clean it every 2 to 3 months to prevent a drop in flow rate
• A noisy or slow filter is often caused by a dirty or damaged impeller

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Frequently Asked Questions

How long should I run my aquarium filter each day? +

Your aquarium filter should run 24 hours a day, 7 days a week. Turning it off even for a few hours can cause the beneficial bacteria inside to die from lack of oxygen, which can lead to dangerous ammonia spikes.

My filter is running but the water is still cloudy. Why? +

Cloudy water in a new tank is usually a bacterial bloom caused by the nitrogen cycle establishing. This is normal and will clear on its own within 1 to 2 weeks. If the water is cloudy in an established tank, check for overfeeding, overstocking, or a clogged filter.

Can I use two filters in one aquarium? +

Yes, running two filters is a great idea for heavily stocked tanks or large aquariums. It also provides a backup if one filter fails, and each filter will house its own colony of beneficial bacteria for extra biological capacity.

What size filter do I need for a 100 litre aquarium? +

For a 100 litre tank, choose a filter rated at a minimum of 400 to 600 litres per hour. For tanks with messy fish like goldfish or cichlids, go for 800 LPH or more. It is always better to over-filter than under-filter your aquarium.

How do I know when to replace my filter media? +

Replace mechanical media like sponges and filter floss when they start to fall apart or cannot be cleaned properly. Never replace all media at once. Replace activated carbon every 3 to 4 weeks. Biological media like ceramic rings rarely needs replacing and should only be changed gradually.

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