Bradders
Member
I have been using the Oase Biomaster 250 (thermal) for over eight months and have had the chance to get up close and personal with the product. I thought it would be good to document my experience for the benefit of others, which may help people use them or find an alternative.
One of the key features is the pre-filter, which is easy to remove and clean and provides protection from too regular a cleaning of the biomedia in the main unit. This can be done in under 10 minutes, which makes weekly maintenance very manageable. Pre-filter foams can be purchased and range from 10PPI to 60PPI.
Oase has decided to keep the units compact to ensure that many of the unsightly pieces of kit (like the heater) remain outside the aquarium. As a result, they fit in smaller cabinets and keep filtration clutter away from the aquarium viewing area. The smallest unit is 24 x 24 x 37 cm. The largest unit is 24 x 24 x 54 cm. Note that Oase scale by going up, not out.
Filtration is supplied in the form of a pre-filter, and then the main unit has 4, 5,6 or 7 trays (depending on the model) of space to add foam, plastic or ceramic media for biofiltration. The main unit houses 20-30PPI foams and HELX-13 plastic media. Every model has pipes, a spray bar, the actual filtration media, and a mix of plastics and foam — everything you need to get started.
The Biomaster Thermal price varies depending on where you look, but they scale from £200 (250 models) to £375 (850 models). This pricing is more aggressive than the Fluval FX series, which ranges from £225 (FX2) to £305 (FX6).
My conclusion is that Oase doesn’t focus significantly on turnover through its filter. 2 or 3 times the aquarium volume is about where they are looking at when looking at their figures for maximum aquarium size for each unit. The Oase Biomaster 250 is recommended for aquariums up to 250L in size. Considering the real-life performance, that could be under 2 x turnover through the unit. The real question is whether (at worst) 2 x performance ensures effective mechanical filtration and biofiltration.
Aquarium Science tested to see if doubling the throughput would double the ability to oxidise ammonia at normal versus 2 x throughput over 90 days. The test averages showed that 2 x throughput was around 9% improved, not 100% improved. The test conclusion showed that flow is not the be-all-and-end-all for ammonia oxidation.
However, there are a few things to consider here.
UKAPS members always emphasise that you require dissolved oxygen at good enough levels to ensure that bacteria in the biofiltration can thrive. Oxygen (especially in a closed system) must reach that bio-media. Furthermore, the ‘flow’ around a planted aquarium (generated by an outflow) is important for environmental health, and 2 x is well below any aquascaper recommendations. As a result, we can conclude that throughput is not paramount for ammonia oxidation but will become an issue in heavily planted and high-tech (i.e. CO2) based aquariums. With the Oase, you may need to add a wavemaker or flow generator in larger aquariums to ensure CO2 is getting effectively pushed around the environment.
Evidence suggests that the more surface area you have, the better chance of cleaner and healthier water for fish. Some research has shown that 100ft/2 (9.3m/2) per metabolic pound (454g) is required to contribute to healthy water for fish. A media's large surface area means there are enough good critters to outcompete bad bacteria – assuming the filter is mature. As a general marker, we will use the 100ft/2 (9.3m/2) per metabolic pound in the rest of this document.
The table below shows fish loading based on 25, 100 and 500 Square Feet on the Oase Biomaster 250. Taking the middle options of 100ft/2, seven 3-inch fish can be supported with enough headroom to deal with the bio-load. (It is worth nothing that the Biomaster 250 can only support 154 grams of fish if using the 100ft/2 target with the supplied media).
The table below shows a typical aquarium with a mixture of fish of differing sizes, as not everyone will have seven fish of exactly 3-inches! You can see from the table that the 27 small fish are supported with the 250’s filter capacity of around 60%. (Note: this example was using the standard 20PPI/30PPI foam and HELX-13 media supplied within the Oase Biomaster 250’s four trays):
When we talk about total capacity for the Biomaster 250, theoretically you could have the following fish loading at the 100 Feet/2 (9.3m/2) per metabolic pound (434g) of fish target. Which represents a nice little community of forty fish in a medium-sized aquarium.
And, if the Biomaster is set up properly and bio-load monitored, it can produce very clear and healthy water for the inhabitants:
The largest unit (the Biomaster 850) has an extra 3 trays when compared to the Biomaster 250. This takes the capacity up to 283 grams of fish at the 100 foot/2 target. That is only an extra 129 fish grams of extra-capacity for a lot more size and cost. Effectively, you would realise more capacity using two Oase Biomaster 250’s. The Oase 850 is the top-end range of Oases’ offering, but it does not come close to the Fluval FX Series in terms of capacity or throughput.
We cannot talk about the scale issue without looking at the design. The Oase Biomaster foams are 7 x 7 x 2 inches, which would provide 98 cubic inches of surface area per tray. However, they lose 29% of space to accommodate the internal heater and the pre-filter housing making the volume only 70 cubic inches per tray. Furthermore, Oase decided to go up, and not go out in terms of their design for larger units. Making the foams 9 x 9 x 2 would have made a significant (and compensating) difference to the capacity. The footprint of the unit would still fit in smaller cabinets and the extra capacity would be welcome. With this design consideration, a single Oase Biomaster 850 would have been able to support 467 grams of fish at the 100 foot/2 target.
This is the price you pay for a canister with a small footprint, internal heater and pre-filter. It is very neat and compact, but you are not going to obtain the same level of filtration capacity that the higher-end Fluval FX series will provide.
That being said, there is no reason that you cannot replace the standard media with, for example, 30PPI foam which will allow for greater filtration capacity. On the Biomaster 250, that would mean a 38% increase from 154 grams to 213 grams of fish at the 100 foot/2 target. And you can always add another Biomaster for redundancy and extra filtering capacity. Running 2 Biomaster 250s in this configuration will give you excellent redundancy and enough filtration for ten 4-inch fish (425 metabolic grams) with clear and healthy water.
Without going into too much detail, the unit has several trays to fill with media and they are all secured with locking clamps and O-rings for watertightness. In-flow and out-flow pipes are connected to the filter and peripherals with locking screws to keep them in place.
Once everything is setup, you can use the primer button to get the water into the canister and therefore removing the air. Once the whole route is saturated with water, you can turn on the unit where it will dissipate the remaining air before returning to normal (and quieter) operation. Depending on how new the model is, there may be a requirement to tilt the unit to really get the last of the air out. (Newer models come with an adapted head plate which improves air removal, and some have reported that it does indeed do a better job). Some have reported problems with the priming function, but it’s very hard to tell whether this is due to the setup or the actual unit. As a result, that potential issue is noted here but without any prejudice toward the Oase design.
Once running, the noise levels are not too invasive. Testing has shown on the 250 and 350 units that it runs at around 41db to 44db, measured at 4 inches away from the head unit. The 350 and above units (which have a larger impeller) tend to run a little nosier. Acceptable noise levels are very subjective as one person’s 41db is too loud, and another person’s very quiet. It would be very difficult to guarantee that it’s a quiet unit as a result.
The pre-filter is very good at making maintenance quick and simple. Depending on loading, average users clean the pre-filter every 7-14 days. A ‘dirty’ pre-filter does tend to reduce the flow so it cannot remain uncleaned for 3 months. However, removing the pre-filter and cleaning really can be reduced to minutes so it is not a major burden. Furthermore, the pre-filter ‘protects’ the main units bio-media, resulting in a cleaning requirement of every 6-12 months or more for the internal media.
The heater seems to function well (providing you have the right wattage for the size of aquarium) and easy to set and forget. The problem here is, when the heater is fitted in the unit, you cannot see the on/off light and therefore don’t have a visual indication that it’s working. When setting up in the summer, you might be left a little confused whether the heater is warming the water, or the weather is! As a result, a basic on-off test should be performed before placing into the unit.
And that is where it all becomes very boring. The unit just sits there removing, cleaning and returning water to the aquarium. Apart from a weekly pre-filter clean, it just blends into the background and becomes somewhat forgotten.
The units can be taken apart very easily (with just a modicum of confidence required) and almost everything can be replaced from the impeller and head plate, right through to the trays which house the media. There are plenty of stockists online and the spare parts are not prohibitively expensive. I have cleaned the impeller, replaced the head plate and replaced the inlet/outlet head section with ease, and without any issues at all. It all feels very accessible and easy to repair or upgrade.
On the upgrade front, Oase does a good job here, too. New head plates, motor plates and pre-filter tubes have been created and they all make some improvement (to varying degrees) to the unit’s performance or operation. This is great news for those with older units who want to upgrade (or modernise) without having to lay out hard earned cash on a new unit. It also shows some ethics from the manufacturer by not forcing you to buy the latest and greatest version.
I have contacted Oase support several times to ask some product-related questions and seek technical advice. They responded promptly and provided reasonable explanations to my questions.
However, for some, I suspect the Oase Biomaster will not be their first choice. The lower turnover rate and capacity could turn people away, especially those with larger environments and more demanding fish loads. There is an argument for not worrying too much about the turnover, but a few extra inches to the design could have significantly increased the media capacity of the units.
Pros
What is the Oase Biomaster
The Biomaster series represents the top end of the Oase range. They are compact units (using height rather than width for range scale) and include space for internal heating devices. The units are available in four sizes, but all function similarly. The only differences are the media capacity and flow rate through the units.One of the key features is the pre-filter, which is easy to remove and clean and provides protection from too regular a cleaning of the biomedia in the main unit. This can be done in under 10 minutes, which makes weekly maintenance very manageable. Pre-filter foams can be purchased and range from 10PPI to 60PPI.
Oase has decided to keep the units compact to ensure that many of the unsightly pieces of kit (like the heater) remain outside the aquarium. As a result, they fit in smaller cabinets and keep filtration clutter away from the aquarium viewing area. The smallest unit is 24 x 24 x 37 cm. The largest unit is 24 x 24 x 54 cm. Note that Oase scale by going up, not out.
Filtration is supplied in the form of a pre-filter, and then the main unit has 4, 5,6 or 7 trays (depending on the model) of space to add foam, plastic or ceramic media for biofiltration. The main unit houses 20-30PPI foams and HELX-13 plastic media. Every model has pipes, a spray bar, the actual filtration media, and a mix of plastics and foam — everything you need to get started.
The Biomaster Thermal price varies depending on where you look, but they scale from £200 (250 models) to £375 (850 models). This pricing is more aggressive than the Fluval FX series, which ranges from £225 (FX2) to £305 (FX6).
Performance
When you think about comments about the Biomaster, one area of concern always pops up. And that is the throughput performance of the units. Many have been disappointed by the manufacturer's L/hour rating and what they see in actual usage. Some people have measured less than 50% of the manufacturer rating, and my personal experience is closer to 66%. (My 250 will output 600 L/hour from the supplier rating of 900 L/hour). And it is worth noting that the turnover will reduce even further as the filter gets closer to needing cleaning.My conclusion is that Oase doesn’t focus significantly on turnover through its filter. 2 or 3 times the aquarium volume is about where they are looking at when looking at their figures for maximum aquarium size for each unit. The Oase Biomaster 250 is recommended for aquariums up to 250L in size. Considering the real-life performance, that could be under 2 x turnover through the unit. The real question is whether (at worst) 2 x performance ensures effective mechanical filtration and biofiltration.
Aquarium Science tested to see if doubling the throughput would double the ability to oxidise ammonia at normal versus 2 x throughput over 90 days. The test averages showed that 2 x throughput was around 9% improved, not 100% improved. The test conclusion showed that flow is not the be-all-and-end-all for ammonia oxidation.
However, there are a few things to consider here.
UKAPS members always emphasise that you require dissolved oxygen at good enough levels to ensure that bacteria in the biofiltration can thrive. Oxygen (especially in a closed system) must reach that bio-media. Furthermore, the ‘flow’ around a planted aquarium (generated by an outflow) is important for environmental health, and 2 x is well below any aquascaper recommendations. As a result, we can conclude that throughput is not paramount for ammonia oxidation but will become an issue in heavily planted and high-tech (i.e. CO2) based aquariums. With the Oase, you may need to add a wavemaker or flow generator in larger aquariums to ensure CO2 is getting effectively pushed around the environment.
Bio-load Capacity
Another topic is how effective the filter will be for a certain quantity of fish. When you add plants into the equation, this is a challenging topic, but for now, we will concentrate on raw filter capability.Evidence suggests that the more surface area you have, the better chance of cleaner and healthier water for fish. Some research has shown that 100ft/2 (9.3m/2) per metabolic pound (454g) is required to contribute to healthy water for fish. A media's large surface area means there are enough good critters to outcompete bad bacteria – assuming the filter is mature. As a general marker, we will use the 100ft/2 (9.3m/2) per metabolic pound in the rest of this document.
The table below shows fish loading based on 25, 100 and 500 Square Feet on the Oase Biomaster 250. Taking the middle options of 100ft/2, seven 3-inch fish can be supported with enough headroom to deal with the bio-load. (It is worth nothing that the Biomaster 250 can only support 154 grams of fish if using the 100ft/2 target with the supplied media).
The table below shows a typical aquarium with a mixture of fish of differing sizes, as not everyone will have seven fish of exactly 3-inches! You can see from the table that the 27 small fish are supported with the 250’s filter capacity of around 60%. (Note: this example was using the standard 20PPI/30PPI foam and HELX-13 media supplied within the Oase Biomaster 250’s four trays):
When we talk about total capacity for the Biomaster 250, theoretically you could have the following fish loading at the 100 Feet/2 (9.3m/2) per metabolic pound (434g) of fish target. Which represents a nice little community of forty fish in a medium-sized aquarium.
| Fish | Quantity |
| Molly (male) | 6 |
| Guppy (male) | 6 |
| Cardinal Tetra (mixed sex) | 12 |
| Platy (male) | 6 |
| Rasbora (mixed sex) | 10 |
| Total | 40 |
And, if the Biomaster is set up properly and bio-load monitored, it can produce very clear and healthy water for the inhabitants:
Scaling
Considering the full Oase Biomaster range, scale could be seen as a challenge.The largest unit (the Biomaster 850) has an extra 3 trays when compared to the Biomaster 250. This takes the capacity up to 283 grams of fish at the 100 foot/2 target. That is only an extra 129 fish grams of extra-capacity for a lot more size and cost. Effectively, you would realise more capacity using two Oase Biomaster 250’s. The Oase 850 is the top-end range of Oases’ offering, but it does not come close to the Fluval FX Series in terms of capacity or throughput.
We cannot talk about the scale issue without looking at the design. The Oase Biomaster foams are 7 x 7 x 2 inches, which would provide 98 cubic inches of surface area per tray. However, they lose 29% of space to accommodate the internal heater and the pre-filter housing making the volume only 70 cubic inches per tray. Furthermore, Oase decided to go up, and not go out in terms of their design for larger units. Making the foams 9 x 9 x 2 would have made a significant (and compensating) difference to the capacity. The footprint of the unit would still fit in smaller cabinets and the extra capacity would be welcome. With this design consideration, a single Oase Biomaster 850 would have been able to support 467 grams of fish at the 100 foot/2 target.
This is the price you pay for a canister with a small footprint, internal heater and pre-filter. It is very neat and compact, but you are not going to obtain the same level of filtration capacity that the higher-end Fluval FX series will provide.
That being said, there is no reason that you cannot replace the standard media with, for example, 30PPI foam which will allow for greater filtration capacity. On the Biomaster 250, that would mean a 38% increase from 154 grams to 213 grams of fish at the 100 foot/2 target. And you can always add another Biomaster for redundancy and extra filtering capacity. Running 2 Biomaster 250s in this configuration will give you excellent redundancy and enough filtration for ten 4-inch fish (425 metabolic grams) with clear and healthy water.
Operation
As mentioned previously, you have everything in the box to get you going. Setup is not too taxing, but it may require a little patience when getting familiar if you are new to external canister filters.Without going into too much detail, the unit has several trays to fill with media and they are all secured with locking clamps and O-rings for watertightness. In-flow and out-flow pipes are connected to the filter and peripherals with locking screws to keep them in place.
Once everything is setup, you can use the primer button to get the water into the canister and therefore removing the air. Once the whole route is saturated with water, you can turn on the unit where it will dissipate the remaining air before returning to normal (and quieter) operation. Depending on how new the model is, there may be a requirement to tilt the unit to really get the last of the air out. (Newer models come with an adapted head plate which improves air removal, and some have reported that it does indeed do a better job). Some have reported problems with the priming function, but it’s very hard to tell whether this is due to the setup or the actual unit. As a result, that potential issue is noted here but without any prejudice toward the Oase design.
Once running, the noise levels are not too invasive. Testing has shown on the 250 and 350 units that it runs at around 41db to 44db, measured at 4 inches away from the head unit. The 350 and above units (which have a larger impeller) tend to run a little nosier. Acceptable noise levels are very subjective as one person’s 41db is too loud, and another person’s very quiet. It would be very difficult to guarantee that it’s a quiet unit as a result.
The pre-filter is very good at making maintenance quick and simple. Depending on loading, average users clean the pre-filter every 7-14 days. A ‘dirty’ pre-filter does tend to reduce the flow so it cannot remain uncleaned for 3 months. However, removing the pre-filter and cleaning really can be reduced to minutes so it is not a major burden. Furthermore, the pre-filter ‘protects’ the main units bio-media, resulting in a cleaning requirement of every 6-12 months or more for the internal media.
The heater seems to function well (providing you have the right wattage for the size of aquarium) and easy to set and forget. The problem here is, when the heater is fitted in the unit, you cannot see the on/off light and therefore don’t have a visual indication that it’s working. When setting up in the summer, you might be left a little confused whether the heater is warming the water, or the weather is! As a result, a basic on-off test should be performed before placing into the unit.
And that is where it all becomes very boring. The unit just sits there removing, cleaning and returning water to the aquarium. Apart from a weekly pre-filter clean, it just blends into the background and becomes somewhat forgotten.
Repair, Upgrades and Support
There is some good news on this aspect of the Oase Biomaster range.The units can be taken apart very easily (with just a modicum of confidence required) and almost everything can be replaced from the impeller and head plate, right through to the trays which house the media. There are plenty of stockists online and the spare parts are not prohibitively expensive. I have cleaned the impeller, replaced the head plate and replaced the inlet/outlet head section with ease, and without any issues at all. It all feels very accessible and easy to repair or upgrade.
On the upgrade front, Oase does a good job here, too. New head plates, motor plates and pre-filter tubes have been created and they all make some improvement (to varying degrees) to the unit’s performance or operation. This is great news for those with older units who want to upgrade (or modernise) without having to lay out hard earned cash on a new unit. It also shows some ethics from the manufacturer by not forcing you to buy the latest and greatest version.
I have contacted Oase support several times to ask some product-related questions and seek technical advice. They responded promptly and provided reasonable explanations to my questions.
Summary
Having lived with two Oase Biomaster 250’s for nearly 9 months, I find myself very fond of this little unit. Space is limited under my medium sized aquarium, and both fit into a paltry sized cabinet. They are quiet, keep the water very clean and are no hassle to maintain. I also appreciate the ability to perform upgrades/repairs which ensure the unit keeps going on for longer.However, for some, I suspect the Oase Biomaster will not be their first choice. The lower turnover rate and capacity could turn people away, especially those with larger environments and more demanding fish loads. There is an argument for not worrying too much about the turnover, but a few extra inches to the design could have significantly increased the media capacity of the units.
Pros
- Small footprint, which fits in smaller spaces.
- Heater and Pre-filter are internal creating neatness.
- Quiet operation, especially for the 250 and 350 models.
- Everything included to get you started.
- Foam and plastic media are of good quality.
- Upgrades and spare parts are freely available and inexpensive.
- The bio load capacity is inhibited due to the design.
- The flow wont please those wanting high turnover.
- Fluval FX series is cheaper, has higher turnover and more media capacity.
- Heater operation light is not visible when fitted.
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