Charles Austen ET40A Pond Air Pump

Charles Austen ET40A Pond Air Pump

The Charles Austen ET40A Pond Air Pump is an alarm equipped version of the trusted Charles Austen ET air pump range. It is designed for ponds, koi filters, septic systems and sewage treatment plants where reliable airflow is essential and where early warning of a fault would be useful.

The key difference between this model and the standard ET40 is the built in low pressure alarm. If airflow is restricted or pressure drops in the airline, the pump can alert you with a loud buzzer and bright LED warning light. This is especially useful on sewage treatment plants and septic systems because the pump is often installed out of sight, meaning a fault may not be noticed straight away.

Although A models are commonly used for wastewater and treatment plant installations, they can also be used on pond systems. For koi ponds, large filters and important holding systems, the alarm gives extra reassurance that airflow loss can be spotted before oxygen levels or biological filtration are affected.

Key features

• Built in low pressure alarm for early fault warning
• Audible buzzer and bright LED warning light
• Reliable airflow for ponds, koi filters, septic systems and sewage treatment plants
• Useful where the pump is installed out of sight or not checked daily
• Oil free air delivery for safe biological aeration
• Weather resistant casing for indoor or outdoor installation
• Compatible with Charles Austen service kits

Technical overview

• Model: Charles Austen ET40A
• Product type: Oil free linear diaphragm air pump with built in low pressure alarm
• Maximum airflow: 40 litres per minute at 0.12 bar
• Power consumption: Approximately 30W
• Power supply: 220V to 240V 50Hz
• Connector size: 14mm
• Noise level: Approximately 40 dB(A)
• Dimensions: 220 x 155 x 190mm
• Weight: Approximately 4.3kg
• Alarm type: Built in low pressure alarm with buzzer and LED warning light
• Common uses: Pond aeration, koi filter aeration, septic systems and sewage treatment plants

Compare Charles Austen air pump ranges

Browse the full Charles Austen ET Series, Charles Austen ETA Series, Charles Austen ETAO Series, Charles Austen ETX Series and Charles Austen CP Series air pumps.

What do A and AO mean? Standard ET models provide reliable continuous aeration. The A versions add a built in low pressure alarm with a loud buzzer and LED warning light. The AO versions add the same built in alarm plus a 230V output cable for connecting to an external alarm panel or beacon. A and AO pumps are generally used on sewage treatment plants and septic systems because the air pump may be out of sight and a fault may not be noticed quickly, but they can also be used on pond systems where extra warning is useful.

Equivalent models

• Charles Austen ET40 Pond Air Pump

Technical details

• Product: Charles Austen ET40A Pond Air Pump
• Brand: Charles Austen
• SKU / product code: ET40A
• Type: treatment equipment
• Check model size, flow rate, connection size and compatibility before ordering.
• Install with suitable supporting equipment and allow access for future servicing.

Maintenance and servicing

Charles Austen state that Pro Series air pumps should be serviced yearly to validate the motor warranty. You can view the correct Charles Austen Air Pump Service Kit options in one place, including genuine replacement diaphragm, filter and valve kits for compatible Charles Austen Enviro ET, ETA, ETAO and ETD models where available. Regular servicing helps maintain airflow, reduce the risk of diaphragm failure and keep your pond, koi or treatment plant air pump running efficiently.

Recommended air diffusers and airline

To get the best performance from this air pump, pair it with suitable large pond and lake air diffuser stations and weighted airline. As a guide, each 10 inch diffuser disc normally works best with around 40 to 50 litres per minute of air. Most single diffuser stations are rated at around 30 to 60 litres per minute, so matching the number of diffuser discs to the pump output helps keep airflow balanced and efficient.

• Suggested diffuser setup: 1 diffuser disc is normally suitable. View the Charles Austen DS1 or Charles Austen DSW1 diffuser station.
• Air manifolds: If you need to split airflow from one pump across multiple airline runs, use the Air Manifold 4mm/8mm/10mm – 2 Way for two runs or the Air Manifold 4mm/8mm/10mm – 4 Way for up to four runs. For Charles Austen air pumps, the 8mm or 10mm outlet options are normally the best choice. The 4mm option is better kept for short, small air stone runs rather than larger diffuser stations.
• Standard sinking airline:
  4mm/8mm Standard Sinking Airline is a practical choice for smaller pond air runs. On Charles Austen pumps we would normally use the 8mm option where possible.
• Heavy duty sinking airline:
  Evolution Aqua Heavy Duty Sinking Airline is the better choice for larger ponds, longer airline runs and high output pumps. For larger Charles Austen pumps, the 8mm or 10mm option is normally the better choice to reduce restriction.

Charles Austen recommend that Enviro air pumps are serviced at least every 18 months. On hard working pond, koi and treatment plant systems, regular servicing helps maintain airflow, reduces the risk of diaphragm failure and supports the manufacturer warranty requirements. Service kits are available for the main ET, ETA, ETAO, ETD and ETX models where applicable.

If you are unsure which service kit suits your pump, contact us and we can help match the correct kit to your Charles Austen model.

Complete your Charles Austen aeration setup

A good aeration system is not only about choosing the air pump. Airline size, diffuser choice, manifold layout and routine servicing all affect the real airflow that reaches the pond. Use the links below to build a complete system rather than buying the pump in isolation.

• Browse the full Charles Austen range
• Browse pond air pumps
• Charles Austen air pump service kits
• Large pond and lake diffuser stations
• Standard sinking airline
• Heavy duty sinking airline
• 2 way air manifold
• 4 way air manifold