Filtration is a prerequisite for optimal aquarium health, and it also spurs the overall wellbeing, survival, and longevity of inhabitants in a captive environment.
Biological filtration works in synergy with chemical and mechanical filtration to keep the aquarium (freshwater/saltwater) balanced, clean and healthy, and hence protect the aquarium fauna and flora from mishaps that could be prompted by adverse conditions such as poor water quality and build-up of ammonia and nitrite.
The nitrification process in an aquarium is facilitated by the presence of biological media including bio balls, activated carbon, ceramic rings or noodles, plants, and porous rocks; these things possess ample surface area for nitrifying bacteria to populate and grow.
This article provides an insight into the nature of aquarium bio balls, and their role in the bio-filtration of aquariums.
| Bio Balls Filter Media – check out the price on Amazon |
What are Bio Balls and How Do They Work?
Basically, bio balls are small, spherical balls made from plastic. And they contribute significantly to biological filtration by providing enough surface area to house huge populations of nitrifying (beneficial) bacteria.
Nitrifying bacteria is responsible for converting harmful ammonia to nitrite, and nitrite into the less toxic nitrates. And what bio ball does is to hold large quantities of this nitrifying bacteria in its surface.
| Rather than conventional, smooth spherical shapes; bio balls are specially crafted to provide additional surface area for beneficial bacteria to live.
These balls are designed in a patterned structure, hence they contain ample spaces or grooves that increase the surface area and enable them to carry even more amounts of nitrifying bacteria. |
Although there are several designs and sizes of bio balls, some even come with an internal bio-sponge; they are all geared towards a specific function — which is to house nitrifying bacteria.
Bio balls are meant to be situated in the filter compartment, and as aquarium water flows over these plastic balls, the nitrifying bacteria they hold oxidizes ammonia and nitrite. The end goal here is to get rid of these toxic compounds, thereby improving the quality of the aquarium water.
How to Use Bio Balls
Do bio balls work completely submerged?
The answer is yes, bio balls can be placed underwater in certain circumstances e.g. when used in large ponds. However, I recommend that you have them above the waterline, preferably in your external filter or aquarium sump.
The bio balls should stay in the canister filter or sump since they are suitable for wet-dry conditions; having water flow over them yet they are not totally submerged.
Placing the bio balls in these aforementioned places exposes them to a constant stream of water which encourages healthy growth of beneficial bacteria, continual dissolved oxygen supply, and increased bio-filtration.
In addition, these balls should be inserted in a secure mesh bag and placed beneath any mechanical filter media such as a filter floss, foam block, or sponge pad. This will help minimize the amount of debris that the bio balls come in contact with, thus keeping them clean and less clogged for prolonged periods.
How Many Bio Balls Do You Need?
As I mentioned earlier, bio balls are available in a variety of shapes and sizes, and that can affect the quantity of bio balls you can fit into an aquarium filter. Opting for small-sized bio balls instead of large ones makes it easier to have more biological media in your canister filter.
There’s a general rule that recommends about 2.2 gallons of bio balls per 100 gallons (about 400 liters) of water. But you can also examine the product packaging to see if there is a stated number of bio balls per gallon of aquarium water.
Be aware that adding fewer balls than recommended will lead to decreased bio-filtration. And it is definitely not a bad idea to have more bio balls than required — provided that the filter chamber can contain them all.
Bio Balls or Ceramic Rings?
These are two widely known biological media, but which is the better option, bio balls or ceramic rings?
First and foremost, let us look at how they both function.
Bio balls are excellent at providing additional surface area for nitrifying bacteria. This filter media can only hold nitrifying bacteria which functions in aerobic conditions; when oxygen is present. Bio balls are made from plastics, so they lack porous spaces and thus cannot carry denitrifying bacteria.
On the other hand, ceramic rings or noodles provide extra surface area for beneficial bacteria through the presence of a multitude of very little pores. Ceramic rings do not only hold nitrifying bacteria, it can as well house colonies of denitrifying bacteria because of their highly porous surface.
This type of bacteria breaks down nitrates into nitrogen gas or nitrous oxide through denitrification in anaerobic conditions i.e. in the absence of oxygen. Also, denitrifying bacteria inhabit porous rocks, ceramics, and other similar materials.
But here’s the catch, the minute pores of ceramic rings can easily be clogged or blocked with dirt than bio balls. And when the longevity of both media is considered, bio balls come out on top because of the plastic build and design.
Regardless, both filter media provide extra surface area for beneficial bacteria to colonize; so whichever option you choose, make sure to perform routine tank maintenance to prevent your biological filter from getting overwhelmed with waste.
Comparison – Bio Balls and Ceramic Rings
| Bio Balls | Ceramic Rings | |
| Surface area | Large | Very large |
| Ease of use | Very easy | Easy |
| Durability | Very Long | Long |
| Nitrifying bacteria | Yes | Yes |
| Denitrifying bacteria | No | Yes |
| Clogging | Slow | Fast |
As we can see Bio ball and Ceramic rings are pretty similar. The main differences are that Ceramic rings can also have denitrifying bacteria in its tiny little pores but, at the same time, these pores can be clogged pretty easily.
Unfortunately cleaning ceramic rings does not always help (because of the size of the pores), and, eventually, some of these pores will be permanently blocked over time. As a result, it will reduce their biological filtration. Whereas, Bio balls can last almost forever.
Lastly, even though, almost every article about Ceramic rings mentions their ability to house denitrifying bacteria as a huge advantage… in reality, we do not have sufficient data. There are no tests that can show us the efficiency of these denitrifying bacteria in Ceramic rings.
Note: In my article “No Water Change Tank?! Top Offs vs Water Change”, I described how denitrifying bacteria can be used as the main filtration in the tank. However, it is not that simple and requires a lot of this type of bacteria.
How to Clean Bio Balls When Dirty
Bio balls will often accumulate dirt in the form of gunk or slime coating within the grooves.
In case you are wondering where this dirt comes from, think of the uneaten fish food, fish poop, decaying plant material, and other suspended particulates in the aquarium water. That’s why it is important to set up your filter with mechanical filtration (e.g. filter floss and sponge pads) before placing the bio balls. Doing so will markedly limit the amount of dirt that gets to the bio balls.
At some point, you will be required to clean the bio balls to let loose of the gunk. Failing to clean them will result in the decomposition of the accumulated organic matter, and this can cause a spike in the ammonia and nitrite levels.
This requires a simple procedure that can be carried out during a water change. Get some quantity of tank water from the aquarium. Insert the bio balls and gently swirl them until you see the dirt coming off. As the dirt particles break away from the bio balls, the water will change from a clear to cloudy form.
Note that scrubbing or wiping action is not required during cleaning as it can remove the beneficial bacteria living on the bio balls. Also, aged tank water remains the ideal water for cleaning bio balls, and be sure not to use tap water or soap/detergent as it can harm and even kill all the established nitrifying bacteria.
Furthermore, you don’t need to replace the bio balls if they are tidy and in good working condition i.e. without any visible sign of impairment. Swapping the bio balls entirely with new ones will remove the established biological filter in your fish or shrimp tank, and that can be quite problematic — sometimes causing the cycling process to start over.
For more information, you can also read “How to Clean an Aquarium Filter”.
In Conclusion
Biological media holds and encourages the growth of bacterial colonies which are responsible for the oxidation of ammonia to nitrite, and nitrite into nitrate. And excess nitrates can be removed from the aquarium through regular, partial water changes.
Bio balls are a great addition to the filtration system and they form a vital part of an aquarium’s biological filtration.
Keep in mind that it may take several weeks for a considerable amount of beneficial bacteria to populate the surface areas. Lastly, bio balls are easily maintained by periodic cleaning in a container of tank water.