OASE Biomaster 250 Canister Filter 2025 Review

I have been using the Oase Biomaster 250 filter for over a year. That’s when I first encountered the Oase brand.

I didn’t know what to expect from this filter, but it made a huge impression on me.

I still use this filter in my 20 gallon aquarium. In this tank I have Cardinal Tetras, Glowlight Tetras, and Siamese Algae Eaters.

I couldn’t wait to share my experiences with this filter with you.

I’m convinced that many of you will choose this filter after reading this review.

I really know what I’m talking about. So here we go.

Review Overview

In short, I am very pleased with this filter. The set includes all the necessary elements for effective water filtration.

Throughout the testing phase, my water parameters remained consistently healthy, with excellent water clarity.

The filter is very well and thoughtfully made. It has a large water priming button and sturdy latches on the motorhead.

It also has a solid big handle on the motorhead, making it easy to carry. I have never met such a filter design.

The filter is also equipped with a pre-filter. This is another feature that sets Oase Biomaster apart from other filters.

The thoughtful design of the pre-filter allows for easy cleaning, as I shown in the pictures below.

However, the most unique feature of this filter is the built-in heater. It has a thermostat that comes out of the motorhead, which allows us to modify the set temperature.

There is nothing easier than turning the thermostat to the right temperature.

I wholeheartedly recommend it, especially for the convenience of the integrated heater, which I absolutely love.

OASE Indoor Aquatics Biomaster Thermo 250

Buy on Amazon

How I tested Oase Biomaster canister filter?

When using this filter, I paid attention to man aspects. Of course, I took into consideration what I discuss in reviews of other filters. I mean:

• Installation
• Priming
• Performance
• Maintenance
• Noise

I tested the above factors both immediately after starting the filter and after several months of use.

It’s not really testing the filter because it has been working in my tank up to now.

So, I can share with you information on how this filter performs after a year of use.

I need to say that installation, priming, and maintenance of Oase Bomaster filter are a breeze.

I paid special attention not only to the high quality of water but also to the appropriate temperature.

This filter works in a 20 gallon aquarium. The tank contains fish:

• Cardinal Tetra,
• Glowlight Tetra
• Siamese Algae Eater

What is included?

The set includes the following items

• motorhead
• canister body
• glass heater
• lift tube with a strainer
• directional nozzle
• spray bar
• hoses and fittings
• user manual
• suction cups

Installation

Installing this filter was simple but slightly different from others I have previously put together.

One noticeable thing is the large handle on the motorhead. I have not encountered such a solution in other filters I’ve worked with . This design allows you to easily move the filter from one place to another.

Oase Biomaster 250 is also equipped with a pre-filter. This is something that sets this filter apart from others that I have tried before.

However, don’t be misled into thinking that this solution can replace a pre-filter as a separate device.

The pre-filter basically consists of a tube that attaches to the bottom part of the motorhead. Inside there are small round sponges that catch debris and gunk before they get into the main canister.

A unique feature of this model is the integrated heater.

A 200 watt glass heater is attached to the engine head. However, please remember that the heater has a separate power cord. Therefore, you will need 2 open electrical sockets for the filter motor and one for the heater.

Using a heater in the filter is a very ingenious solution. First of all, fish and other creatures do not come into contact with a direct source of heating. This will protect our fish from possible overheating.

In addition, the heater in the filter allows for more even heating of the water column.

And most importantly, we don’t have to take up space directly in aquarium.

Every aquascaper strives to minimize the visibility of equipment in the tank as much as possible. The less equipment, the more the focus is on fish and plants.

You must read the user manual before using this filter. It’s important to remember that the glass heater can crack and cause burns.

Exercise extra caution during maintenance.

We need to unplug the heater from the power cord and wait for it to cool down before pulling it out of the water.

You can find more information on this in the safety recommendations provided by the manufacturer.

The filter canister is divided into four stacking baskets stacked on top of each other. Three of the baskets contain reusable sponges, while the last one contains biomedia that resembles ceramic noodles but is made of white plastic.

It is recommended by the manufacturer to install the canister with the provided media.

When installing this filter, I used completely different biomedia. I chose those that contain a large number of nooks and crannies where beneficial bacteria can grow.

The manufacturer provided a very large amount of mechanical media. I think there are too many of them, but the filter design allows for easy media configuration.

Instead of one sponge, I used additional media to improve water transparency. I chose zeolite which has the ability to absorb and exchange ions and reduces nitrites and water.

The manufacturer provided a very large amount of mechanical media. I think there are too many of them, but the filter design allows for easy media configuration.

Instead of using just one sponge, I added extra media to improve water clarity. I opted for zeolite, which has the ability to absorb and exchange ions, reducing nitrites and nitrates in the water.

You need to know that over time, zeolite loses its absorption capacity, so it should be replaced regularly.

What filter media you use depends only on you. You don’t have to use zeolite here like I did.

Zeolite works best with other filter media, such as ceramics, filter sponges or activated carbon.

Priming

The first time priming this filter wasn’t as straightforward as with other ones I’ve used.

Of course, what is immediately noticeable is that the motorhead has a large priming button.

After installing the entire filter, I pressed the button with my hand. The hand-pump made it look like it would be “easy priming”.

I thought I was in pretty good shape, but I had to use my forearm to start water flowing into the canister

During maintenance, I no longer had any major problems with filter priming. All I had to do was reconnect the hoses and water automatically started flowing back into the canister.

I have found opinions that removing filter air may be problematic. I have been using this filter for almost a year and have never had any problem with it.

Generally, you can hear the filter blowing air sporadically. However, I never had to shake it or prime it to clear the air.

Performance

The filter maintains excellent water clarity in my aquarium at all times. The pre-filter effectively captures small particles from the water column.

The remaining sponges catch additional impurities. Throughout the entire period of use, my water parameters are stable. I change the water in the aquarium every week and clean the pre-filter every few weeks.

When it comes to the GPH test, the manufacturer declares a flow rate of 250 GPH. Typically, manufacturers state this as the value the filter motor can pump without filtration materials and other obstacles.

In this case, it took less than 23 seconds to fill one gallon container. This means whether the filter can pump out approximately 165 gallons per hour.

Of course, with my subsequent GPH measurements it started to drop. This is, of course, due to the fact that the filter media may be clogged.

Therefore, the dirtier the filter media, the slower the GPH will be.

Even though the water flow is not a big problem, I think it could be much bigger. This is enough for my needs in my fish tank.

According to the manufacturer, the filter can be used for aquariums up to 70 gallons. I believe it will work much better in aquariums up to 50 gallons.

Of course, I couldn’t forget about how the integrated heater performed. I keep the average temperature in my aquarium at 80°F (26C).

The built-in heater integrated with the filter maintains a constant temperature at all times. I have absolutely no complaints about temperature control.

I wonder how the heater would handle much higher temperatures and a larger aquarium.

Setting the right temperature on the heater doesn’t guarantee uniform temperatures throughout the water column.

Therefore, monitoring the temperature with a thermometer, preferably one with a probe, is necessary.

Maintenance

Maintaining and cleaning this filter couldn’t be easier. In fact, this is for me the only filter that’s so easy to clean.

Cleaning the pre-filter takes less than 5 minutes. We don’t have to get wet and we don’t have to worry about dirty water getting into the fish tank.

We can wash the pre-filtr whenever we want because it takes a very little time and we can use any water to rinse the sponges.

We usually use water from the fish tank for rinsing. In this case, however, it does not matter because all the bacteria are safely contained in the canister.

By cleaning the pre-filter with tap water, we do not kill beneficial bacteria.

We also do not have to open the entire container to clean the filter. While the pre-filter can be cleaned more often, the internal filters can be cleaned much less frequently.

To clean the pre-filter, we must unlock it on the motorhead by moving the lever to the unlock position.

Maintenance is made much easier by the handle on the motorhead.

After blocking and disconnecting the hoses, it is of course very simple, we can grab the filter by the handle and move it to the place where we want to clean it.

Moving a container filled with water is usually very unpleasant. Most canister filters are difficult to clean.

Of course, we must remember to unplug the heater and wait until it cools down before you pull it out of the filter.

Noise

This is the quietest filter I have ever had the pleasure of using. The average reading from the meter showed 48.5 decibels.

Of course, you should pay attention to the fact that it has been working for several months now.

Nevertheless, the noise level is very low. I took the measurement not only at the filter canister itself, but also in the room where the filter is located.

It is known that we do not put our ear to the filter and listen to it, so it is also important to measure it in normal conditions. The filter is closed in a cabinet under the fish tank.

The measurement in the room was only 43 dB. I would describe the noise produced by this filter as very slight hum. I think that even for very sensitive people it will not be a major problem.

Even if the filter is placed in the bedroom, I think it is the quietest I have ever had. Eheim Classic or Fluval 207 filters emit much more noise.

Pros and Cons

I wondered for a long time what to write in this section. It is difficult to find any major disadvantages with this filter.

How does Oase Biomaster compare to other filters?

Compared to other filters, Oase Biomaster has 3 unique features that none of its other competitors have. Specifically, I’m talking about:

• sturdy handle on the motor head
• built-in heater
• ingenious and intuitive cleaning of the pre-filter

The handle on the motorhead makes it easy to carry it even when it is full of water,. It provides greater stability and facilitates maintenance.

The built-in heater eliminates the need to install it inside the tank. This way we do not take up space in the aquarium, it does not disturb composition, and the fish are safe.

The ingenious and intuitive pre-filter cleaning method distinguishes it from brands like Fluval or Eheim.

In terms of mechanical filtration, only Fluval filters can compare with Oase Biomaster. The set includes many reusable sponges to effectively capture contaminants from the water.

However, I must admit there’s limited space for biomedia. Therefore, as I wrote earlier, I took out one of the sponges and added biomedia myself and changed the configuration.

I didn’t mention it before, but a cool feature is flow regulation built into provided piping.

This is a solution I haven’t seen in other filters.

Therefore, we do not have to regulate the flow directly on the motorhead.

So, we can adjust outflow, inflow or just cutoff floe on the canister itself.

We can use spray bar or normal outflow pipe.

Fluval, Marineland, or Eheim filters have more space for biomedia. Fluval provides the perfect balance between mechanical and biological media.

One of the elements that was missing in this filter was a central handle with which I could pull out all the baskets at once.

In a filter of this class, such a handle would perfectly complement its practicality.

This solution is known to us from Fluval filters. You don’t need to put your hands into dirty water to remove baskets.

When it comes to noise, this is by far the filter that has the lowest decibel reading.

OASE Indoor Aquatics Biomaster Thermo 250

Buy on Amazon

Who is the Oase Biomaster Canister Filter Best For?

I would recommend this filter for fish tanks no more than 50 gallons.

The actual GPH is lower than declared by the manufacturer. So, we can use this filter for small and delicate fish.

I really like the built-in heater in this filter. This solution will be perfect, for example, for fry. We will protect the fish from contact with a hot surface and we will not have to worry about the temperature of the water in the aquarium.

Moreover, the filter is very compact. Anyone who doesn’t have much space will be able to cope with its location. The handle on the motorhead will help with maintenance.

It seems to me that it is worth investing in this filter, especially if you plan to keep tropical fish.

I am very pleased with the performance of this filter and I don’t think I would replace it with any other.

Even though I have other brands in other aquariums, this one holds a special place in my heart.

In conclusion

I have the 250 thermal, and it’s the most outstanding filter I’ve ever had.

The standout feature is the pre-filter, making it incredibly easy to remove and clean without having to take the whole filter apart.

I’m extremely satisfied with its performance and have no intention of replacing it.

If needed, I would happily purchase another model from Oase.

I trust you find this review useful. If you’ve got any questions about this filter, feel free to ask – I’m here to assist.

Wishing you and your fish nothing but the best!