Charles Austen ET 120 Air Pump — 120 LPM Professional-Grade Aeration for Large Hydroponic Systems
Best for: Growers scaling up to larger reservoirs or multi-system setups who need reliable, continuous aeration without the noise
Our thoughts
This is proper kit. Linear diaphragm design, whisper-quiet operation, built for 24/7 duty, and designed to last. You're looking at industrial-grade reliability at a price that makes sense for serious hobbyists and early-stage commercial growers. One we recommend a lot to people outgrowing their 70 LPM pump.
The Charles Austen ET 120 is a professional-grade linear diaphragm air pump delivering 120 litres per minute of clean, oil-free air. Built for continuous duty operation, it's designed to sit at the heart of larger deep water culture systems, multi-reservoir setups, or any growing operation where reliable aeration isn't negotiable.
Unlike smaller aquarium-style pumps that lose pressure over time, the ET 120 maintains consistent output day in, day out. At just 35dB, it's also one of the quietest high-capacity pumps on the market — a genuine advantage if you're growing in a residential space or anywhere noise matters.
How it compares
The ET 120 sits in the semi-commercial to serious hobbyist tier, bridging the gap between entry-level hobby pumps and ultra-industrial units.
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vs. Small hobby pumps (40-70 LPM): 70% more output, professional-grade reliability, linear diaphragm design (quieter, more consistent), replaceable service parts, designed for 24/7 continuous duty
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vs. Mid-range commercial (110 LPM): Comparable output, significantly quieter (35dB vs. 45-60dB), lower power draw, oil-free by design, UK-backed 2-year warranty
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vs. Ultra-commercial (150+ LPM): Overkill for most UK growers; ET 120 hits the sweet spot for scaling without overspending
Bottom line: you're getting industrial reliability at a price that doesn't assume you're running a commercial operation.
Usage guidance
System sizing
As a general rule, you want at least 1 litre of air per minute for every gallon of water. The ET 120's 120 LPM output suits single large reservoirs (120+ gallons), multi-bucket DWC systems, or expanding setups where you're planning growth. If you're running smaller individual systems, this pump gives you room to add more without replacing it.
Installation
Connect the supplied L-shaped rubber connector to the pump's 18mm outlet. You'll need a separate manifold (sold separately) to split the airflow to multiple air stones via standard 4mm airline tubing. Secure tubing with the included hose clips. Never immerse the pump itself in water — it sits outside your reservoir.
Air stone setup
Run airline tubing from the pump through the manifold to submerged air stones in your reservoir. This distributes oxygen evenly and prevents stagnant water, which kills roots. More air stones = better coverage, especially in larger reservoirs.
Continuous operation
The ET 120 is built for 24/7 duty. Unlike intermittent-rated pumps, it won't overheat or degrade from constant running. Dissolved oxygen needs to stay consistent — this pump delivers that without flinching.
Maintenance
Charles Austen recommend servicing every 18 months. Service kits (including replacement diaphragms) are available separately and significantly cheaper than buying a new pump. It's a genuine advantage of this design — you can keep it running for years with basic upkeep.
Technical specifications
- Air output: 120 litres per minute (at 0.12 bar)
- Noise level: 35dB (extremely quiet for continuous operation)
- Power consumption: 90–125 watts
- Design: Linear diaphragm, oil-free
- Outlet connector: 18mm brass screw-in
- Supply voltage: 220–240v, 50Hz (UK standard)
- Weight: 4kg
- Dimensions: 265mm (L) × 215mm (W) × 198mm (H)
- Included: Screw-in brass connector, L-shaped elbow, 2 hose clips
- Warranty: 2 years (UK-backed)
- Rated for: Continuous duty (24/7 operation)
- Thermal cut-out: Built-in protection
Who this is for
- Growers moving from 70 LPM setups to larger single reservoirs or multi-system operations
- Semi-commercial operations running 5+ buckets or tanks requiring reliable redundancy
- Anyone prioritising 24/7 reliability over initial cost — can't afford system failure
- Residential or noise-sensitive growers (the 35dB operation is a genuine edge)
- Growers who want a pump they can service and repair rather than replace
- UK-based operations who value local warranty support
Our take
This is a properly engineered pump designed to work reliably for years. The linear diaphragm design isn't new — it's been used in hydroponics for decades because it works. You're not paying for hype or brand premium; you're paying for consistency and the confidence to run it 24/7 without babysitting it.
The 35dB noise level is worth highlighting — most competitors in this output range run at 45–60dB. That's the difference between background hum and something you notice. The 2-year UK warranty and availability of service parts also separate this from disposable alternatives that force you to buy a new pump when something wears.
If you're scaling up your growing operation and want air pump anxiety off the list, this is worth picking up. Good time to buy while stock lasts.
