Air Pump vs Filter Fish Tanks: What is the difference?

When setting up a new aquarium, two of the most important equipment considerations are air pumps and filters. But what exactly is the difference between the two? And when should you use one, the other, or both? This comprehensive guide dives into all you need to know to decide if your fish need bubbles or crystal-clear water – or maybe both!

What’s an Air Pump?

An air pump does exactly what the name implies – it pumps air! Air pumps are small electric devices that push air through tubing into the tank, exiting through an airstone, creating bubbles.

The main purpose of an air pump is to increase surface agitation. This agitation allows gas exchange at the surface, where Oxygen in the air can dissolve into the water. This is extremely important, as fish “breathe” dissolved Oxygen in the water through their gills. Running an air pump ensures your aquatic pets always have enough Oxygen available.

Where’s the Best Place to Put It?

Proper placement is crucial to get the most out of your air pump! The ideal location is at the bottom of the tank. This allows the bubbles to travel the full height of the water column, exchanging gases equally from bottom to top.

Do I Need to Run It 24/7?

Continuous operation of your air pump isn’t always necessary. The ideal duration depends on factors like tank size, livestock, and whether you have live plants. Tanks densely packed with fish need more oxygen circulation than sparsely stocked ones. And plants generate Oxygen during photosynthesis, reducing the demand.

Observe your tank during the day and night. If the surface appears stagnant or fish are gulping at the top, increase aeration. An air pump timer can be used to run it only during peak oxygen use times.

What Does a Filter Do?

While air pumps add Oxygen, filters remove waste. Aquarium filters pull water through mechanical, biological and chemical filtration media to maintain pristine water quality.

Mechanical media like sponge or floss traps debris, sifting it from the water column. Biological media harbors beneficial bacteria that break down toxic ammonia and nitrite. Chemical media like activated carbon absorbs odors, discoloration, and some medications. The varying media types combine to keep the water sparkling clean and safe for your finned friends!

Are They the Same Thing?

It’s easy to confuse the two, but air pumps and filters perform very different jobs! Air pumps oxygenate while filters clean. Think of it like the lungs and kidneys of your aquarium – both vital to aquatic life!What Size Tank Needs Which?

One of the biggest factors on pump vs filter is tank size. Let’s look at the recommendations:

Small Tanks: 10 gallons or less

For small starter tanks, a filter is usually adequate on its own. The lower water volume and bioload don’t typically create an oxygen shortage. Just watch for signs of trouble like surface film.

Medium Tanks: 10-40 gallons

The higher water volume in mid-size tanks starts to warrant more gas exchange. An air pump can be beneficial, especially when plants aren’t producing Oxygen at night.

Large Tanks: Over 40 gallons

Running a filter and air pump is highly recommended for larger aquariums. The ample water volume makes Oxygenation from surface agitation a priority. A filter alone can’t manage waste and sustain oxygen levels.

Do I Need an Air Pump AND a Filter?

Adding air and filtration systems might seem redundant, but each serves a vital purpose. Think of it like eating a balanced diet – different nutritious foods working together to create good health!

Using both devices is extremely beneficial for tanks over 10 gallons, or any tank with a high bioload. The air pump constantly replenishes Oxygen to support life, while the filter scrubs away waste.

The combo allows the filter to focus on its mechanical and chemical duties without creating surface agitation for gas exchange. And the air pump doesn’t have to pull double duty trying to oxygenate AND trap debris.

What Are the Benefits of Air Pumps?

Air pumps have several advantages:

  • Increased Oxygenation – more air in the tank means higher Oxygen for livestock
  • Low Maintenance – air pumps have no filter media to clean or replace
  • Cost Effective – air pumps are an affordable way to upgrade small tanks
  • Gentle Flow – the bubbles are soft and gentle, safe for delicate fish like bettas
  • Versatile – they can power sponge filters, air-driven ornaments, etc.

Are Air Pumps Good For All Fish Tanks?

While air pumps have clear benefits, they aren’t a universal solution. Here are a few things to consider:

  • It only Adds Oxygen – doesn’t filter water or remove waste like filter media
  • Can Be Noisy – the electric motor and bubbling can generate noise
  • Requires Ongoing Electrical Use – filters can run off a powerhead during power outages
  • Higher Temperature Water Holds Less Oxygen – may need more vigorous agitation in tropical tanks

Combining an air pump’s advantages and disadvantages makes them an excellent supplemental option for most tanks over 10 gallons. A quality filter is still essential for smaller nano aquariums, and air can play a secondary role.

Using Air Pumps and Filters Together

Adding an air pump alongside your filter gives you the perfect pairing! The filter handles the mechanical and chemical filtration to keep water pristine. The air pump takes care of churning the surface to increase that all-important Oxygen.

This combo works great for larger tanks, heavily stocked aquariums, reef systems with corals, turtle habitats, and low-flow betta tanks. Clean and well-oxygenated water is vital to animal health in these challenging environments.

Other Uses for Air Pumps

Beyond just adding bubbles, air pumps have a variety of helpful uses:

  • Power air-driven decorations like treasure chests and scuba divers
  • Drive air-powered sponge filters for quarantine and hospital tanks
  • Add movement to low-flow betta tanks with airstones or bubble wands
  • Increase water circulation without strong currents
  • Improve gas exchange in planted tanks at night when plants aren’t producing Oxygen

Air Pump or Filter: Which is Better?

When it comes to air pumps vs. filters, there’s no universally “better” option. The right choice depends entirely on the needs of your unique aquarium environment.

For very small nano tanks under 5 gallons, a quality filter is likely adequate on its own. Medium tanks may benefit from adding supplemental air at night or during heavily stocked periods. Most large tanks over 40 gallons require ideal water quality and Oxygenation.

Observe your aquarium and livestock. If you notice signs of low Oxygen, like fish gasping at the surface, an air pump is a wise addition. Cloudy water, debris accumulation, and high nitrates signal it’s time to upgrade or supplement filtration.

Every tank is different, so let your livestock be the guide! Provide both the bubbles and crystal clear water needed to thrive.

Getting the Right Size Pump and Filter

Size and capacity are crucial factors when selecting an air pump or filter. An undersized model can’t adequately service the tank, while an oversized unit wastes energy and is unnecessarily costly. Follow these guidelines:

Air Pumps

Match air pump output to tank volume. Look for:

  • 10-20 gallon tanks: 20-60 L/hr pump
  • 20-40 gallon tanks: 60-100 L/hr pump
  • 40-100 gallon tanks: 100-200 L/hr pump
  • 100+ gallon tanks: 200+ L/hr pump

Other factors like depth, stocking level, and decorations can increase requirements. When in doubt, go a size up for extra airflow.


Filter capacity depends on both tank size and stocking level. Lightly stocked tanks need less filtration than heavily loaded ones.

Look for a filter rated at least 2-3 times your aquarium’s volume for average stocking levels. Up to 5 times for extra filtration.

Other Tips:

  • More media = more space for bacteria = higher capacity
  • Opt for adjustable flow rates
  • Allow for future livestock additions

Maintenance Requirements

Air pumps and filters both require regular maintenance for optimal performance. Here’s what’s needed:

Air Pumps

  • Wipe salt creep and algae buildup monthly
  • Check all connections are secure
  • Replace aging air tubing

Aquarium Filters

  • Rinse mechanical media monthly to unclog pores
  • Replace chemical media like carbon every 4-6 weeks
  • Only rinse biological media in old tank water
  • Clean intake strainer of debris buildup

Following the manufacturer’s maintenance schedule keeps the equipment running efficiently for years. Test water parameters routinely to confirm filtration is working properly.

Adding Supplemental Aeration

If your filter has an integrated spray bar or produces surface ripples, it may provide sufficient aeration in gentle stocked tanks. But there are easy ways to upgrade:

  • Position the filter outlet higher at the water’s surface to increase agitation
  • Attach an air stone to the filter intake to diffuse air bubbles into the water
  • Use an air pump with a dual outlet to power both an airstone and sponge filter

This supplemental aeration prevents the filter from working overtime to manage waste and Oxygenation singlehandedly. More air exchange means less stress on biological filtration.

Power Outages and Battery Backups

One downside of air pumps is they require continuous electrical operation. Power failures can be disastrous without a battery backup system. Here are a few solutions:

  • Battery-powered air pumps provide several hours of aeration
  • Uninterruptible power supplies (UPS) power equipment for short outages
  • Battery-operated air diffusers temporarily add surface agitation
  • Gasoline generators can run equipment for extended multi-day outages

Meanwhile, most filters can operate off battery-powered powerheads or air pumps for hours. Combining the two creates a reliably oxygenated and filtered environment during electrical failures.

Monitoring Water Quality

To confirm your air and filtration devices are performing properly, routinely test water parameters. Target levels should be:

  • Ammonia and Nitrite: 0 ppm
  • Nitrate: <40 ppm in freshwater, <20 ppm in saltwater
  • pH: 6.5-8.5 in freshwater, 8.0-8.4 in saltwater
  • Temperature: Appropriate for species
  • Dissolved Oxygen: >5 ppm

Consistently ideal readings mean your biofiltration and Oxygenation fully support the tank inhabitants. Time for a water change!

Troubleshooting Common Issues

Equipment issues arise eventually in any aquarium. Here are some quick troubleshooting tips:

Air Pump Troubles

  • No airflow – Check connections and power supply, replace tubing
  • Too many/few bubbles – Adjust air valve, clean airstone
  • Loud noise – Lubricate pump, tighten parts, replace worn pump

Filter Problems

  • Reduced flow – Clean clogged media and intake strainer
  • Leaking – Check seals and connections and replace them if worn
  • Trapped debris – Remove obstruction, upgrade intake strainer
  • Cloudy water – Increase water changes, upgrade filter capacity

Keys Takeaway

The difference between air pumps and filters and when and how to use them. To summarize:

  • Air pumps add Oxygen through surface agitation
  • Filters remove waste and clarify water
  • Small tanks may only need a filter
  • Medium and large tanks benefit from both devices
  • Together, they provide optimal water quality and Oxygenation

Every aquarium needs clean water and ample air. Understanding your options allows you to customize life support for your underwater pets! You can now make the most informed choice whether it’s bubbles or sparkling clarity you’re after, or maybe both. Your fish will thank you!


Choosing between an air pump, filter, or using both depends on your tank’s specific needs. Focus on your aquarium size, livestock type, oxygen demands, and filtration requirements. Address any issues that arise promptly to maintain a healthy underwater environment. This guide’s advice lets you make the best decision for your fins and scales!