OASE BioMaster² external filter for aquariums up to 850 litres
The OASE BioMaster² is an external canister filter for freshwater and marine aquariums from 150 to 850 litres. Water passes the EasyClean pre-filter first. It traps coarse dirt in a module you lift out and rinse without opening the main canister. The water then flows up through filter sponges and Hel-X bio media, where beneficial bacteria break down ammonia and nitrite.
This is the BioMaster² without a heater. For sizes 150 to 850, you can also buy it with the heater already fitted: see the OASE BioMaster² Thermo. Every size, including the 150, has room inside the canister to add an OASE HeatUp heater later.
Which BioMaster² size do I need?
| Your aquarium | Choose | Max flow |
|---|---|---|
| Up to 150 L | BioMaster² 150 | 850 l/h |
| Up to 250 L | BioMaster² 250 | 900 l/h |
| Up to 350 L | BioMaster² 350 | 1,100 l/h |
| Up to 600 L | BioMaster² 600 | 1,250 l/h |
| Up to 850 L | BioMaster² 850 | 1,500 l/h |
If your tank is heavily stocked or holds large, messy fish, pick the next size up. For a gentle planted tank, use the included flow regulator to turn the flow down.
Key features
- EasyClean pre-filter module: catches coarse dirt before it reaches the main media, so the biological stage stays clean for longer.
- Two-stage filtration: 30 and 45 ppi sponges for mechanical cleaning, Hel-X elements for biological filtration.
- Higher flow than the first BioMaster: wider water paths and a new inlet and outlet set.
- Priming button: fills the canister with water for a quick start after setup or cleaning.
- Safety shut-off: the valves close when you disconnect, so water does not spill.
- Quiet running and low energy use, from 15 W on the 150 and 250.
- Complete set: ready to use out of the box.
Technical data
| Model | Up to | Max flow | Max head | Power | Filter volume | Pre-filter vol | Size L×W×H mm |
|---|---|---|---|---|---|---|---|
| BioMaster² 150 | 150 L | 850 l/h | 1.7 m | 15 W | 3.2 L | 0.3 L | 240×240×315 |
| BioMaster² 250 | 250 L | 900 l/h | 1.7 m | 15 W | 4.4 L | 0.4 L | 240×240×370 |
| BioMaster² 350 | 350 L | 1,100 l/h | 1.4 m | 18 W | 5.6 L | 0.5 L | 240×240×425 |
| BioMaster² 600 | 600 L | 1,250 l/h | 1.8 m | 22 W | 6.8 L | 0.6 L | 240×240×480 |
| BioMaster² 850 | 850 L | 1,500 l/h | 2.2 m | 32 W | 8.0 L | 0.7 L | 240×240×535 |
All models: 230 V / 50 Hz, hose connection 16/22 mm (inner/outer), 1.5 m power cable, suitable for freshwater and saltwater. Warranty 3 years, plus 1 extra year when you register the filter with OASE.
What’s in the box
BioMaster² filter with pre-filter module, filter sponges and Hel-X media, hose (2.5 m with the 150, 4 m with the larger sizes), adapters, flow regulator, intake and outflow pipes, and water diffuser.
Adding a heater later
Every BioMaster² has space for an OASE HeatUp heater inside the canister, so there is no heater in the aquarium. Matching sizes: 150 → HeatUp 100, 250 → HeatUp 150, 350 → HeatUp 200, 600 → HeatUp 300, 850 → HeatUp 400. For sizes 250 to 850 you can also buy the BioMaster² Thermo with the heater already fitted.
Frequently asked questions
What is the difference between the BioMaster² and the BioMaster² Thermo?
They are the same filter. The Thermo version comes with an OASE HeatUp heater already installed inside the canister, so you have no heater in the tank. The standard BioMaster² on this page has no heater, but you can add one later.
Which BioMaster² size is right for my aquarium?
Match the model number to your tank volume in litres: the 150 for tanks up to 150 litres, the 250 up to 250 litres, and so on. If your tank is heavily stocked, choose the next size up.
Is the BioMaster² 150 too strong for a small tank?
No. The 150 is made for aquariums up to 150 litres and comes with a flow regulator. On a smaller planted tank, turn the flow down so plants and small fish are not pushed around.
Can I add a heater to the BioMaster² 150?
Yes. The 150 takes an OASE HeatUp 100 inside the canister. There is no Thermo version of the 150, so the heater is bought separately.
How often should I clean the BioMaster²?
Rinse the pre-filter module every 2 to 4 weeks, depending on how many fish you keep. Clean the main sponges and Hel-X only every few months, and rinse them in old tank water so you keep the good bacteria.
Can I use the BioMaster² in a saltwater aquarium?
Yes. OASE rates every BioMaster² model for both freshwater and marine aquariums.
What is new compared with the first OASE BioMaster?
The BioMaster² has wider water paths and a new inlet and outlet set, which give a higher flow rate. It also adds a compact 150 model for aquariums up to 150 litres.
What warranty does the BioMaster² have?
OASE gives a 3-year warranty. Register the filter with OASE to get one extra year.
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