If you are new to aquariums, an air pump, air stone and sponge filter can look like three separate pieces of equipment.
In reality, they are often part of the same simple system.
The basic setup is:
Air pump → airline tubing → check valve → sponge filter or air stone
The air pump pushes air through the tubing. That air then powers either an air stone or a sponge filter.
The important difference is this:
An air stone mainly improves aeration and water movement. A sponge filter provides filtration as well as aeration.
This makes the combination of air pump + sponge filter one of the simplest and most useful filtration setups for betta tanks, shrimp tanks, breeding tanks, quarantine tanks and smaller freshwater aquariums.
What Does an Air Pump Do?
An aquarium air pump sits outside the tank and pushes air through airline tubing.
The pump itself does not usually go into the water.
It provides airflow for equipment such as:
- Air stones
- Sponge filters
- Bubble walls
- Air-driven ornaments
- Undergravel filters
The amount of airflow depends on the pump's power, tank depth and how many devices are connected.
What Does an Air Stone Do?
An air stone connects to the airline tubing and breaks the airflow into smaller bubbles.
These bubbles rise through the aquarium and create:
- Water movement
- Surface agitation
- Improved gas exchange
- Visible aeration
The main oxygen benefit comes from the movement created at the water surface.
An air stone does not provide meaningful mechanical or biological filtration by itself.
So if your tank only has an air stone, you may still need a proper filter.
What Is a Sponge Filter?
A sponge filter is a simple aquarium filter made from porous sponge material.
Most sponge filters are powered by an air pump.
As bubbles rise through the filter's lift tube, they pull aquarium water through the sponge.
This creates continuous water flow through the filter media.
The sponge then performs two important jobs.
Mechanical Filtration
The sponge traps:
- Fish waste
- Uneaten food
- Fine debris
- Suspended particles
Biological Filtration
Beneficial bacteria colonise the sponge.
These bacteria help process waste through the aquarium nitrogen cycle.
This means the sponge filter can support the conversion of:
Ammonia → Nitrite → Nitrate
How Does a Sponge Filter Work?
The process is surprisingly simple.
Step 1: The air pump pushes air
Air travels through the airline tubing.
Step 2: Air enters the sponge filter
The bubbles rise through the centre or lift tube.
Step 3: Rising bubbles move water upward
This creates a lifting effect.
Step 4: Aquarium water is pulled through the sponge
Water passes through the porous sponge material.
Step 5: Debris is trapped and beneficial bacteria process waste
The sponge provides both mechanical and biological filtration.
Step 6: Water returns to the aquarium
The rising bubbles also create surface movement and aeration.
So one simple device provides:
Filtration + circulation + aeration
Air Stone vs Sponge Filter: What Is the Difference?
This is one of the most common beginner questions.
Air Stone
Main purpose:
- Aeration
- Bubbles
- Water circulation
- Surface agitation
It does not provide significant filtration.
Sponge Filter
Main purpose:
- Mechanical filtration
- Biological filtration
- Aeration
- Gentle water circulation
Both can be powered by the same type of aquarium air pump.
If your goal is just additional oxygenation, an air stone may be enough.
If you also need filtration, a sponge filter is usually more useful.
Do You Need an Air Stone Inside a Sponge Filter?
Sometimes.
Some sponge filters already contain an internal diffuser or are designed to produce bubbles without a separate air stone.
Others can be fitted with an air stone inside the lift tube.
Adding an air stone may help create:
- Smaller bubbles
- Smoother airflow
- Reduced bubbling noise
- More consistent water movement
Whether you need one depends on the specific sponge filter design.
What Equipment Do You Need for a Sponge Filter Setup?
A complete air-powered sponge filter system usually includes:
1. Air Pump
Creates the airflow.
2. Airline Tubing
Carries air from the pump to the aquarium.
3. Check Valve
Helps prevent aquarium water from flowing backward toward the pump.
4. Sponge Filter
Provides mechanical and biological filtration.
5. Optional Air Stone
May improve bubble size and airflow depending on the filter design.
6. Optional Air Control Valve
Allows you to reduce or adjust airflow.
This is especially useful for bettas or shrimp that prefer gentler water movement.
Why Is a Check Valve Important?
A check valve is a small one-way valve installed in the airline tubing.
Its job is to help stop water from flowing backward toward the air pump.
Back-siphoning can happen if:
- The power goes out
- The pump stops
- The pump is positioned below the aquarium water level
If water reaches the pump, it can damage the equipment and create an electrical hazard.
For this reason, using a check valve is a simple and inexpensive safety measure.
Always make sure it is installed in the correct direction.
How Should the Setup Be Connected?
The basic order is:
Air pump → airline tubing → check valve → airflow controller if needed → sponge filter
For an air stone:
Air pump → airline tubing → check valve → air stone
If one pump powers multiple devices, you can use:
- Splitters
- Gang valves
- Multi-outlet pumps
Make sure the pump is powerful enough to supply all connected equipment.
Can One Air Pump Run Both an Air Stone and Sponge Filter?
Yes.
A sufficiently powerful air pump can operate multiple devices.
For example:
One air pump → splitter → sponge filter + air stone
However, airflow will be divided between them.
If one device receives too little air, you may need:
- A stronger pump
- Flow adjustment
- A better splitter
- Shorter airline tubing
- Fewer connected devices
How Strong Should the Airflow Be?
More bubbles do not always mean better filtration.
The ideal airflow depends on:
- Tank size
- Sponge filter size
- Water depth
- Fish species
- Number of filters
- Desired current
For bettas, fry and shrimp, the airflow should usually be gentle.
For larger or more heavily stocked tanks, stronger flow may be useful.
The goal is steady water movement without stressing the livestock.
Why Are Sponge Filters So Popular for Betta Tanks?
Bettas often prefer relatively gentle water movement.
Strong filter currents can make swimming difficult, especially for long-finned bettas.
A sponge filter provides:
- Gentle filtration
- Good biological filtration
- Aeration
- Low suction risk
- Adjustable flow
That makes it particularly suitable for many betta setups.
Why Are Sponge Filters Good for Shrimp Tanks?
Sponge filters are also extremely popular with shrimp keepers.
They provide:
- Gentle water flow
- No strong intake
- Biological filtration
- Surfaces for microorganisms
- Biofilm for grazing
- Safe filtration for baby shrimp
Shrimp often pick at the sponge surface because microorganisms and fine food particles accumulate there.
Why Breeders Use Sponge Filters
Sponge filters are commonly used in breeding and fry tanks.
Traditional filter intakes may accidentally suck in tiny fry.
Sponge filters have a much gentler intake surface.
They also provide stable biological filtration without creating excessive current.
For this reason, they are popular for:
- Betta fry
- Guppy fry
- Shrimp babies
- Small breeding tanks
- Nursery tanks
Can a Sponge Filter Be the Only Filter?
Yes, depending on the aquarium.
A properly sized sponge filter can be sufficient for many:
- Betta tanks
- Shrimp tanks
- Small community aquariums
- Breeding tanks
- Quarantine tanks
However, larger or heavily stocked aquariums may require additional filtration.
The best filter depends on:
- Tank volume
- Fish load
- Feeding
- Waste production
- Desired water clarity
Does a Sponge Filter Clean the Water as Well as Other Filters?
A sponge filter is excellent for biological filtration and basic mechanical filtration.
However, it may not polish the water as finely as systems using fine filter wool or multiple filtration stages.
For tanks where crystal-clear water is the priority, some hobbyists combine a sponge filter with:
- Hang-on-back filter
- Canister filter
- Fine mechanical media
The sponge filter can then provide backup biological filtration and aeration.
How Often Should You Clean a Sponge Filter?
A sponge filter should be cleaned when:
- Water flow noticeably decreases
- The sponge becomes heavily clogged
- Large amounts of debris accumulate
Do not clean it too aggressively.
Beneficial bacteria live on and inside the sponge.
A common method is:
- Remove some aquarium water during a water change.
- Place the sponge in that water.
- Gently squeeze it several times.
- Return it to the aquarium.
Avoid trying to make the sponge look brand new.
The goal is to remove excess debris while preserving beneficial bacteria.
Should You Wash a Sponge Filter Under Tap Water?
It is generally safer to rinse biological filter media using aquarium water removed during a water change.
Untreated tap water may contain disinfectants such as chlorine or chloramine, which can damage beneficial bacteria.
If tap water is used, make sure it is properly treated with an appropriate water conditioner.
What Size Sponge Filter Should You Buy?
Choose a sponge filter based on:
- Aquarium volume
- Stocking level
- Amount of waste
- Available space
- Desired flow
It is often better to choose a slightly larger sponge filter than one that is too small.
Larger sponge filters generally provide:
- More biological surface area
- Greater debris-holding capacity
- Better filtration potential
What Size Air Pump Should You Use?
The air pump should be strong enough to push air through the sponge filter at the tank's depth.
Consider:
- Tank height
- Number of sponge filters
- Number of air stones
- Tubing length
- Splitters
- Flow-control valves
If the bubbles are very weak, the pump may be undersized or losing pressure through the system.
Why Is My Sponge Filter Not Bubbling?
Check the following:
Air pump power
Make sure the pump is running.
Airline tubing
Look for bends, leaks or loose connections.
Check valve direction
A backwards check valve can block airflow.
Clogged air stone
If the filter uses an internal air stone, it may need cleaning or replacement.
Too many devices
One small air pump may not have enough pressure for several filters.
Tank depth
Deeper water requires more pressure.
Why Is My Air Pump So Noisy?
Air pumps can create vibration.
To reduce noise:
- Place the pump on a stable surface
- Avoid placing it directly against the aquarium glass
- Use a soft anti-vibration mat
- Check that the casing is not touching other objects
- Make sure the pump is not overloaded
- Inspect tubing for restrictions
Sometimes an undersized pump working at maximum pressure can also become noisier.
Does a Sponge Filter Increase Oxygen?
Yes.
Because it uses rising air bubbles, a sponge filter increases water movement and surface agitation.
This encourages gas exchange.
However, the biggest oxygen benefit still comes from the surface movement rather than the bubbles simply dissolving into the water.
Can You Use a Sponge Filter Without an Air Pump?
A traditional air-driven sponge filter needs an air source.
Usually, this means an aquarium air pump.
Some specialised sponge filters use a powerhead instead, but standard models rely on air-driven lift.
Without airflow, the filter will not circulate water properly.
Do You Need Both an Air Stone and Sponge Filter?
Not always.
If your sponge filter already provides enough aeration, an additional air stone may not be necessary.
You might still add one if:
- You want extra aeration
- The tank is heavily stocked
- Water temperature is high
- Fish need stronger oxygenation
- Medication is being used
- You want more surface movement
Best Simple Setup for Beginners
For many small freshwater aquariums, a beginner-friendly setup is:
Air pump
↓
Airline tubing
↓
Check valve
↓
Sponge filter
This setup provides:
- Aeration
- Water circulation
- Mechanical filtration
- Biological filtration
It is simple, inexpensive and easy to maintain.
Products You Need for the Complete Setup
At YASAM Pets, a complete air-driven filtration setup can include:
Aquarium Air Pump
Provides the airflow.
Airline Tubing
Connects the pump to the filter.
Check Valve
Helps prevent backflow.
Sponge Filter
Provides filtration and aeration.
Air Stone
Useful for additional aeration or some sponge-filter configurations.
Airflow Control Valve / Splitter
Useful when adjusting flow or running multiple devices.
Buying these components together makes it much easier to build a compatible aquarium aeration system.
Frequently Asked Questions
Does a sponge filter need an air pump?
Yes, most traditional sponge filters require an air pump to create water flow through the sponge.
Can I connect an air stone directly to an air pump?
Yes.
Connect the air pump to the air stone using airline tubing, preferably with a check valve installed.
Is an air stone better than a sponge filter?
They serve different purposes.
An air stone mainly improves aeration.
A sponge filter provides both filtration and aeration.
Can one air pump run two sponge filters?
Yes, if the pump provides enough airflow.
Use a splitter or gang valve to divide the air supply.
Can a sponge filter replace a normal filter?
For many small or lightly stocked freshwater aquariums, yes.
Larger or heavily stocked systems may benefit from additional filtration.
Should the air pump be above the aquarium?
Positioning the pump above the water level can reduce back-siphon risk.
If it is below water level, use a correctly installed check valve.
Final Thoughts
An air pump, air stone and sponge filter are closely related, but they do different jobs.
The easiest way to remember them is:
Air pump = creates airflow
Air stone = turns airflow into bubbles for aeration
Sponge filter = uses that airflow to provide filtration and aeration
For many aquarium keepers, the most useful setup is:
Air pump + airline tubing + check valve + sponge filter
This gives you a simple system that supports water movement, beneficial bacteria and oxygenation at the same time.
For betta tanks, shrimp tanks, breeding setups and smaller freshwater aquariums, it is one of the most practical filtration systems available.
YASAM Pets carries aquarium aeration and filtration accessories so you can build the full system using compatible components rather than buying each part without knowing how they connect.