Resun AC-9603 is an air pump for aquariums of 50 to 400 L. It delivers 270 L/h while drawing just 5 W. It has two air outlets and a flow regulator, so you can run two air stones or use one outlet for a smaller tank. It measures 183×97×67 mm and fits on a cabinet beside the tank. The box contains the pump with its regulator and two outlets; airline tubing, air stones and check valves aren't included and are sold separately.
Why an aquarium needs an air pump
Air bubbles themselves add little oxygen, but they stir the water and boost gas exchange at the surface: oxygen goes in and carbon dioxide comes out. That matters most in well-stocked tanks, in hot weather, during medication and at night, when plants consume oxygen. On basic equipment, see aquarium for beginners: what to buy.
Key specs
| Parameter | Value |
|---|---|
| Type | air pump |
| Output | 270 L/h |
| Power | 5 W |
| Outlets | 2 |
| Flow regulator | yes |
| Tank size | 50–400 L |
| Dimensions | 183×97×67 mm |
| Brand | Resun |
Pros
- Efficient. 5 W for 270 L/h.
- Two outlets. Two air stones or two tanks.
- A flow regulator. Turn the flow down.
- A wide range. 50–400 L tanks.
- Compact. 183×97×67 mm.
- Sits outside. Takes no space in the tank.
Cons
- No tubing or air stones. Buy them separately.
- A check valve is needed. To stop water draining into the pump.
- It hums. Like any diaphragm pump.
- At the limit for 400 L. Use two air stones in a big tank.
What else to buy
You'll need airline tubing of the right length, one or two air stones or airline bars, and a check valve for each line. A check valve stops water siphoning back down the tube into the pump if it switches off or the power fails. This is especially important if the pump sits below the water level.
How to install it
Place the pump on a cabinet or shelf beside the tank, ideally above the water level. Connect tubing to the outlet, fit a check valve, and put an air stone on the end, either on the bottom or attached to the glass. If you use one outlet, block the other or turn the flow down. A soft mat under the pump reduces vibration and noise.
Setting the flow
Use the regulator to get visible surface movement without blowing fish around. Small, slow fish such as bettas dislike strong currents. For shrimp tanks and fry, use a fine air stone and a gentle flow.
Air pump and filter
Many internal filters already oxygenate water through a spray bar or venturi. An air pump complements the filter where oxygen runs short: in an overstocked tank, in hot weather or during medication. It can also drive air-lift sponge filters. To support the biology, use beneficial bacteria too, such as Tetra Bactozym.
One outlet or two
Two outlets help in several cases: in a large tank you can place two air stones in different corners for even aeration; you can run an air stone and a sponge filter; or you can serve two small tanks, such as a main tank and a breeding tank. For one small tank, a single outlet is enough — turn the extra flow down with the regulator.
Care
Check the tubing for cracks from time to time and replace the air stone when it clogs and produces large bubbles. The pump's diaphragms wear over time — if the flow drops noticeably, they can be replaced. Keep the pump dry.
Who it suits
Owners of 50–400 L aquariums that need extra aeration — heavily stocked tanks, hot weather, medication periods and sponge filters. All equipment is in the aquarium equipment section.
Verdict
The Resun AC-9603 is an efficient 270 L/h air pump drawing 5 W, with two outlets and a flow regulator for 50–400 L tanks: compact, it sits outside the tank and runs two air stones. The downsides are that tubing, air stones and check valves must be bought separately, and it hums while running.
FAQ
What tank size is it for?
50 to 400 L.
What's the output?
270 L/h.
How much power does it use?
5 W.
How many outlets?
Two, with a flow regulator.
What's included?
The pump with its regulator; tubing and air stones are sold separately.
Do I need a check valve?
Yes, to stop water draining into the pump.
What are the dimensions?
183×97×67 mm.
