Ziss Bubble Bio ZB-300 Bubble Moving Media Filter: Product Review

The Ziss ZB-300 Bubble Bio: The world's first hobby-sized commercial fluidized filter! - by
4 / 5 Stars

Short Take

Let our little goldfish paste give you a quick intro...

Although cleaning your filter can be something that's fun to do on a lazy Sunday morning when you're feeling relaxed and have the time, dealing with a clogged filter late on Thursday night when you want to be in bed can be the last thing you want to deal with.

As a result, why not choose filters that are a bit more forgiving when it comes to maintenance?

Enter the Ziss ZB-300 Bubble Bio filter.

As one of (if not the) first examples of a commercially available "fluidized bed filter", the Bubble Bio filter is a largely self-cleaning biological powerhouse. With media tumbling over itself continuously knocking off debris and an easy-to-clean, fry safe intake filter, it's going to be hard to beat for both low and high bioload tanks.

It's perfect for aquariums up to 40 gallons on its own or as part of a complete filter system for much larger tanks.

The ZB-300 can be purchased right now from Aquarium CoOp in the US, Aquarium Direct in Canada, and (if you don't mind waiting forever and paying quite a bit more) worldwide from Ebay.

Ziss ZB-300 Bubble Bio Filter
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Come take a look to see if it's right for your tanks!

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Here's an example of how I'm using our first test filter. It's being used along with sponge filters in a 75 gallon aquarium containing a breeding trio of ryukins.

Why Would I Consider Using the ZB-300?

As I said in the intro, the main advantage of the Ziss Bubble Bio filter is that it should require less maintenance than other types of aquarium filters in the same size.

In addition, knowing when you need to do maintenance is easy since you'll see the media start to slow down as the intake sponge filter starts to clog. Ideally you'll clean it before that point, but life gets busy for the best of us sometimes!

For me personally, I'm a goldfish breeder and am used to managing high bioloads in breeder tanks. Since goldfish spawns are so large and it takes a while to figure out which fish are the real keepers, I end up keeping tanks that are more heavily stocked than most hobby keepers would want to manage.

As a result, the Ziss Bubble Bio filter is a particularly interesting option on account of it being easy to maintain and capable of handing an intense biological load. Ammonia spikes in grow out tanks aren't something I can tolerate since they affect the health of fish during critical growth times, and given our little ones have food in front of them almost 24/7 that's a real risk.

This is also still a good choice for planted tanks like my oto breeding setup as well however, since it helps to keep the water oxygenated and handles the low bioload there with ease.

So far, so good!

Why Is The ZB-300 A Big Deal?

There's a fair amount of hype around the ZB-300 filter right now compliments of some fairly innocent comments by Cory from Aquarium CoOp:

Cory had to make an entire video on the ZB-300 after a few small posts on Facebook started the internet on fire (lol)

Is the ZB-300 really something to get that excited about though?

Personally, I'm clearly curious enough to try one, but not yet excited enough to tear out all the filters in my fish room to replace them with these guys.

This is partially because they're a good chunk more expensive than the $10 sponge filters I normally use, and partially because my tanks need a lot of mechanical filtration to remove suspended debris floating in the water (read: goldfish poop).

If I was in the market for a filter for a filter for a planted tank or a community tank, however, this filter would be on my short list.

As I gain experience with it I may still end up using more of them, so stay tuned for updates based on long-term use.

Either way, the ZB-300 is particularly  remarkable because it's the first time fluidized bed filters have been adapted for small to medium tanks for non-DIYers (for people who buy filters rather than make them)

What Is a A Fluidized Bed Filter?

A fluidized bed filter is one where a bed of media is kept in constant motion by either water or (as in our case) air. This presents a number of advantages over a filter where the media is sitting still, including:

  • being in constant movement, the media is always bumping against itself. This knocks off debris, and keeps it clean and available for filter bacteria to grow on.
  • by being in constant motion, there are no "blocked" surfaces that water flow (and therefore ammonia and other waste products) can't get to. This means that all surfaces of the media are used fully
  • with ample food and a steady stream of air from the bubbler system, bacteria have an ideal environment in which to grow. As a result, some people have reported that this style of filter cycles quicker than other filters might
  • unlike something like a trickle tower, the media stays perpetually wet. In the event of a loss of power the media may pack down temporarily, but it should never dry out in an ideal world.

Since they get a lot of effectiveness out of every ounce of media they contain, these filters can provide a lot of biological filtration capacity (ability to convert ammonia to nitrite and then nitrate). As a result, they're likely to provide more bio filtration benefit compared to other filters of the same physical size (most people say this version is good up to about a normally-stocked 40 gallon aquarium).

These are also amazing filters for breeder tanks, where rapidly growing fish are accompanied by rapidly growing waste levels. More than a lot of other styles of filter, these fluidized bed filters should be able to keep pace with changing waste levels with relative ease. This means no potential growth is lost to ammonia or nitrite buildup.

The ZB-300 even packs on an intake filter to protect baby fish and those with long fins against damage from the filter intake.

What Maintenance Should A ZB-300 Require?

Unlike other filters where the media requires constant flushing with used tank water during water changes, the swirling media beads in this filter should never require cleaning under normal use.

To protect the media (though it doesn't really need it), keep fish and small fry out,  and mainly to provide SOME element of mechanical filtration, the filter also comes with an intake sponge located on the lower end cap of the filter.

During each water change that sponge should be removed and rinsed. A quarter turn twist of the cap removes it, and it can be cleaned with no danger of the fluidized media spilling out from the inside due to it being contained in another chamber.

The sponge is made of decent material, and seems well suited to the job. It's nice and coarse (has large pores) so it doesn't clog too quickly, but is still capable of polishing the water to a usable degree.

When servicing the sponge, take a large ziplock bag, submerge it in water, and wrap it over the lower part of the filter before removing the sponge cap. This will help to contain the debris which will be released when you twist off the cap.

If you keep the air running until right before you twist the cap off, you'll make sure that only a minimum of debris ends up escaping back into the tank. Even if you're not perfect in containing that debris, rest assured any cloudiness in the water will clear up very quickly after putting the filter back into operation.

With heavy bioloads like goldfish provide, the sponge needs cleaning each week in order to prevent the sponge from clogging. In a community or planted tank it may be possible to extend the period between cleanings.

In either case, make sure to clean the sponge before the media stops moving properly. The media window allows you to easily see this as it happens, so there shouldn't really be a reason to ever end up with an issue.

What About Build Quality?

Build quality on this unit is really very good, which makes up a huge reason for why it stands head and shoulders over a DIY pop bottle version.

DIY pop bottleversions of these filters are definitely effective, but can sort of look like you dropped some trash in your aquarium

The plastic used on the housing is solid and heavy-duty, and should be thick enough to hold up to wear for years. Pop bottle versions can actually wear through and fail in that time, which requires you to make new housings (admittedly not a big deal, but it never happens when you actually have time to make a new filter).

The black plastic housing of the ZB-300 blends in to the black painted aquarium backgrounds that a lot of aquarists favor to make fish colours pop, and the semi-transparent window allows you to see media movement without being too obvious about it. The window even comes already tinted in an "algae friendly" color, which while not super attractive when clean, blends in well later on as the aquarium matures.

The top cap of the ZB-300 removes with a pop by using a little rocking action and some effort, and allows access to the media chamber.

The filter comes complete with Ziss ZM-1 micro moving media. This material was custom designed and made by Ziss, and is reported to fluidize better than the usual Kaldness K1 micro media DIYers have used for years.

Some people have even experimented with replacing the media with Biohome or other options, but I haven't found any reports on whether that works any better than the standard ZM-1.

The cap itself has "bubble groves" molded into it that gather and guide the air bubbles from the lower section of the case and shuttle them out into the aquarium. They're a neat feature, and helps prevent air buildup within the cap itself.

Moving down the case we find a solid air intake tube which links the filter to an air pump that you supply. I'll touch on what air pumps work best in the next section, but suffice to say the connection is solid and should hold up to years of use.

The suction cups on any device that relies on them can be a real point of frustration for a lot of people if they're not of decent quality. I have many heaters which no longer reliably stick to their walls, for example, and so I inist on only the best if I'm forced to use something that relies on suction cups now.

I'm happy to say that the suction cups on the ZB-300 are very good, and though I intentionally didn't even bother to clean the glass of my test aquarium to really put them through the ringer, they grabbed tenaciously and it takes a lot of effort to make them let go. They unfortunately don't have the little helper tabs some suction cups come with which make removing them easier after they grab, but those tabs always seem to end up in the wrong spot when you need them so not having them isn't really much of a loss.

As an added point in favor of purchasing through Aquarium CoOp, Cory has commented that he will replace any suction cups that don't hold up properly to use, and he stocks a regular supply. If you were debating on ordering from him vs eBay, this is another point in favor (plus shipping speeds from Aquarium CoOp are basically impossible to beat). You should never need the replacements from what I can tell, but it's nice to know the option is there.

Lastly, the lower section of the ZB-300 filter is another exercise in both quality and attention to detail. It contains both the removable cap and sponge filter as well as a basic air diffuser.

The removable lower sponge cap twists on and off with only a small rotation, and the lock and cap are both solid units.

The built in diffuser is very neat, and is basically a very coarse version of similar items you might see that are intended for dispersing CO2 into a planted aquarium.

The advantage provided by including the little puck diffuser is that it provides a wider "spray" of air bubbles compared to what a simple tube might allow. That wider bubble spray causes the media to start moving quicker and stay in motion longer on a smaller amount of air, limiting the power required to operate the filter.

All in all, the ZB-300 is a solid little unit.

What Air Pump Does It Require?

Although when you first hook the filter up to an air pump and try to get the media to move it may seem like it's going to require a lot of air to do so, once the media has been submerged and seeded for a few hours, the air flow required by the filter is actually very moderate.

As a result, it should match well with any medium output hobby pump.

In terms of what that might mean, my favorite hobby pump right now is the Fluval Q2:

Fluval Q2 Air Pump
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It's only a few dollars more than its smaller cousins the Q1 and Q0.5, and puts out more air in return.

The main advantage of the Q2 is that the output is adjustable, which is really nice for this filter. Being able to adjust the pump for the minimum flow required to keep the media moving helps to minimize the noise this filter creates, which can be a concern for some people.

The smaller pumps will likely run the filter just fine (especially for smaller, shallower tanks), but don't have the same adjustability. You can just throttle the air flow with the included air valve, but that creates back pressure on the pump and can reduce the life of diaphragm type pumps (which most small hobby pumps are).

A much better plan than relying on the filter air valve is to have a pump which has it's own adjustability built in, since the pump will be designed to be throttled properly that way.

How Big Of An Aquarium Can the Ziss Bubble Bio Filter Handle?

Like with any other filter capacity spec, how big of an aquarium the ZB-300 can handle is a little bit of a loaded question.

If you plan to lightly stock your tanks with a small group of community fish and lots of plants, you're probably going to be more limited by the filter's ability to circulate water than by how much filter bacteria it can grow.

For heavily stocked tanks (ie goldfish tanks), you'll probably eventually get to the point where the biological capacity of filter (how much ammonia it can process) limits things before circulation does.

All that said, this filter should be good to about a decently stocked 40 breeder sized tank if used as the only filter in the aquarium. The box media claims it's good to 300L (80 US gals), but I would think that might be pushing things if your stocking level is high.

Used in concert with another filter like a sponge, canister or hang on back, you can go much larger with good results.

In terms of physical size, remember that the filter itself is 10" tall and is designed to be mounted vertically. That means any aquarium in the 12" tall or smaller range will be a poor choice to use this filter with, and eliminates 5, 10, and 20 gallon long tanks. 20 gallon high and larger tanks will do fine.

I've personally used this filter so far as the only unit in a lightly stocked 65 gallon planted tank, and on a heavily stocked 75 gallon goldfish tank alongside sponge filters for additional mechanical and biological filtration. Both setups have done well.

Is The ZB-300 Shrimp and Fry Safe?

It should be; at least for all but the most sensitive fry.

The most important part of making a filter safe for fry is to ensure that they can't be sucked into an intake or motor. The ZB-300 has no motor, and has an intake sponge filter that's appropriately designed to keep most fry out.

The filter might not be the best choice for breeding fish that build bubble nests just because the surface disruption it creates would affect the nest, and fish that have super tiny fry might conceivably manage to get through or stuck in the foam, but for 99% of breeding operations it should be a decent choice.

What Are The Downsides to The ZB-300?

While the ZB-300 would make a great filter for a large number of different types of setups, it's certainly not perfect nor a perfect choice for every tank.

Here are some considerations you should be aware of before committing to a potential purchase.


The number one complaint I hear from new owners of this filter is that they're "extremely" noisy. I suspect that some of these folks have just never used air powered filters before, but it's worth taking a closer look at the noise issue just be clear.

First off, the noise produced by bubbles bursting on the surface is almost impossible to completely eliminate. This is true for bubbles regardless of the source, so any complaints in that line of thinking would equally apply to sponge filters, box filters, air stones, bubble curtains, and anything else that creates a bubble stream.

As a result, if you need an absolutely silent filter for a bedroom or entertainment room, something like a canister filter might be a better option (here's a link to my complete guide to filter choices if you need more ideas).

If you want to keep this filter and make it as silent as possible, one clever user reported that it was much quieter if the outlet at the top of the filter was kept above the water surface (so the bubbles burst inside the filter rather than outside of it).

That said, I think the problem most people are encountering when using this filter is that they're feeding it too much air in an attempt to get the media moving quickly. The huge stream of air creates a lot of noise, and isn't actually required to operate the filter correctly.

When you first connect the filter to your air pump, you might be tempted to really blast the air stream to get things moving. Doing so won't really hurt anything, but using a slower air flow just requires a little patience (about a day) to result in gentle swirling of the media.

Especially once the media is moving, very little air is actually required to keep the media moving. Since the smaller the air stream is the less noise it creates, those that want to create as little noise as possible might want to look to see if they're over-driving their filters in burst of initial excitement.

The media in the ZB-300 doesn't actually need to be bouncing around like ping pong balls in a dryer, but rather just needs to be evenly moving to ensure that it stays clean and aerated. Faster bubble rates will cause more circulation and draw more water through the filter (creates a quicker turnover rate), but aren't strictly required to make the filter operate properly.

Compared to other air filters like sponge filters and box filters with airstones the bubble size the ZB-300 emits is a little on the large side. Since bigger bubbles tend to be louder when they burst, this may be a source of the complaints about noise.

Since the filter actually requires less air overall then some of those other options however (I run mine on less air flow than my sponges for example), I don't personally notice much difference in noise between this and a sponge filter.


Cost is a consideration in any purchase, and this filter fits into a little bit of an odd spot in the market.

Compared to power filters like canisters and hang on backs of about the same capacity or "size rating", it's certainly not expensive.

Compared to air powered filters of similar capacity, however, it's a fair bit more (~$30 from most sources vs ~$10 for a box or sponge filter).

That said, the build quality is absolutely outstanding, and biological filter capacity is potentially far greater (for a proportionate loss of mechanical filtration capacity). It's just the reality of a small-batch made in Korea product pitted against huge-batch made in China competitors.

Personally, I find the ZB-300 a decent choice for someone with a few display or special needs tanks.The cost shouldn't be an issue if you only have a handful of aquariums in your collection, but it might be a bit of a budget stretcher if you're outfitting an entire fish room with them.

One Size Fits Some

Since the filter is 10" tall and can't really be installed at much of angle while still being able to function properly, this limits the range of tanks which can use the ZB-300.

Most 5 gallon and 10 gallon tanks are going to be a little too short as a result, as are 20 gallon long aquariums. 20 gallon high and larger tanks should have no issue.

How Much Does Your Water Level Drop During Water Changes?

It's also worth considering that, even if the filter fits when the aquarium is full, if you do large water changes you'll have to be careful about not leaving it to dry out when the tank is drained. A short period of exposure will probably be okay, but letting the media dry out will mean you need to start cycling the aquarium again.

If you size your aquarium so that the filter isn't exposed even at low water level (or you use a continuous drip system that doesn't change the water level) then this isn't an issue.

It's Not Exactly Small

Related to the above, at 10" tall and 3" wide the filter isn't exactly compact.

As a result, a large rock, piece of wood, or a mature sword plant is going to be required if you don't like to be able to see your filter.

Even a moderately sized sponge filter hides away easier than this guy.

Not Everyone Is Down With Booger Yellow

Although most people will agree that crystal clear hoses and lily pipes look lovely when clean, not everyone has the patience to keep them clean.

Clear pipes full of algae on the other hand (the usual result of a missed scrub or two) don't look nearly so nice.

As a result of this reality of human behavior, Ziss decided on the not-exactly-lovely yellow tint for the transparent media window on the finished ZB-300 product. It blends in to most aquariums that have even a touch of algae, and doesn't really change color much if the owner of said aquarium decides to leave it alone for a while.

Although not my favorite color in the world, I can at least respect the choice of yellow. Smoked black plastic might have been a better option in my book, but I can live with the yellow myself.

Your mileage may vary.

Planted Tanks And CO2

Some people will object to the use of this filter in a planted tank that uses CO2 injection out of fear that it will help to off-gas the CO2. Personally, I think it's a bit of a non-issue.

First off, I've spoken to a number of respected folks in the planted tank community (specifically Tom Barr and Cory McElroy) and neither sees any real issue with air options and planted tanks.

Yes, it will require a very tiny addition of extra CO2 to offset the potential loss, but it also helps to assure that proper oxygen levels are maintained.  CO2 is very inexpensive, so going to great lengths to conserve it is pretty silly.

Air powered filters likewise help to maintain oxygen level and off gas CO2 PRODUCED by plants (and fish) overnight when they aren't photosynthesizing, so particularly if you don't turn your CO2 off overnight, this is can actually be a good thing.

That said, if you're paranoid about this issue, be aware that (like anything that creates bubbles) that may require you to very slightly adjust your CO2 flow. It'll benefit you in a number of other ways as mentioned above, but I thought I should at least mention this consideration.

Don't Try to Use A Hammer To Drive In Screws

Fluidized bed filters excel is providing exceptional biological filtration. What this means is that they're extremely efficient in converting ammonia produced by your aquarium into nitrite, and then to nitrate.

Where they're not as ideal is if your application requires a lot of mechanical (debris removal) or chemical (the ability to run Purigen or activated carbon easily) filtration. The ZB-300 does have a sponge to provide some mechanical filtration, but it's not particularly large and is coarse to avoid needing constant maintenance.

As a result, if you need either of those other types of filtration, you may be better off running a different filter or having something like a box filter on hand to use.

Lee's Triple Flow Corner Box Filter
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Box filters aren't particularly attractive, but they're cheap, simple, and will run off the same air pump as the ZB-300 if you buy one that's powerful enough (the Fluval Q2 mentioned earlier will be fine).

If it's a temporary use (carbon to remove medication, for example), then the appearance of a box filter is a limited inconvenience.

If you don't mind the appearance of the box filter (they're easy to keep clean since you can see when they're getting dirty), then they make an amazing choice for polishing your water to crystal clear clarity or for keeping fry tanks clean. In concert with a ZB-300 you'd have all your filtration bases covered. 

Maybe Not the Best Choice If Power Is Sketchy in Your Area

If your area is prone to having extended power outages, a fluidized bed filter like the ZB-300 might not be the best option (go with something like a sponge filter).

After power losses you'll want to be sure that the media starts circulating again. Particularly if you're running the filter on low air flow to keep it quiet, you'll want to give it quick check when the power comes back.

If the media doesn't stay in motion, it can pack down and cause bacteria loses as it starves for oxygen.

This is also worth considering if you're going to be rescaping a tank and will have the tank drained for a number of hours. In that case, it would be worth running the filter inside a bucket of water or the like so that the media stays oxygenated and swirling.

Can't I Just Make My Own Fluidized Bed Filter?

Absolutely! If you don't mind the slightly "functional" look of an old pop bottle in your aquarium, they're quite straightforward to make.

You'll get most of the benefits at some cost in ease of cleaning and appearance.

Here's a great video by AquaPros on how to make your own fluidized bed filter. You could even buy and use the media that the ZB-300 runs if you'd like.

What Are Other People Saying About The ZB-300?

If you're looking for a few other opinions on what people are thinking of the ZB-300, check out the following YouTube videos.

As linked earlier, here's Cory from Aquarium CoOp's review of the ZB-300

A review of the ZB-300 by Weldon Aquatics

Bob Steenfott's epically cinematic take on a ZB-300 review

Conclusion - Is The Ziss ZB-300 Bubble Bio Filter Worth Buying?

Personally, I have zero regrets so far buying this filter. It's solidly built, does the job it's designed to do, and is available at a reasonable price. 

I'm giving it a 4 out of 5 stars just because of the price. It's not a huge amount of money, but within its bracket (air powered filters) it's on the top end of cost.

If I only had a few tanks to filter, those tanks were particularly sensitive, or I needed super low maintenance option this would be a solid choice.

Since I run a number of tanks at home however, the $30 price tag puts it solidly above that of the $10 sponge filters I normally run in most tanks. As a result, though I'll continue to use the ZB-300 and may even pick up another couple later on, I probably won't be converting all my tanks over anytime soon.

That said, if you want a great filter that not only works well but is a bit of a conversation starter for your friends, the Ziss ZB-300 is tough to beat!

Ziss ZB-300 Bubble Bio Filter
If you click these links and make a purchase, we earn a commission at no additional cost to you. We use those commissions to purchase additional products to review, and to help pay the water bill around here :)


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