# What is the point of biomedia in filters?



## chinaboy1021 (May 30, 2003)

Nitrifying bacteria is limited by the amount of bioload/ammonia in the tank right? 

Can somebody tell me why we put biomedia in our filters when the same nitrifying would establish itself in our substrate and plants otherwise? Also is there any benefits to having excessive biomedia?

A bit confused regarding this...:iamwithst


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## Blackheart (Jul 5, 2011)

I never understood the point or need to use biomedia. I use HOB filters with nothing but sponges and have never had any issues with anything. That's just me though.


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## hollo (Jun 14, 2014)

I'd argue more is better than less, if you have the capacity for more nitrifying bacteria, then in case you add more livestock or if there is an ammonia spike, the bacteria has a way of expanding and growing numbers.
Also, from what I remember nitrifying bacteria _doesn't_ establish itself on plants? It's limited in the substrate due to the lack of oxygen in deeper levels, from what I remember as well.

Personally I prefer using biomedia for a good bacteria load, sponges both for bacteria and coarse mechanical filtration and then filter floss to filter out the finer things.


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## GrampsGrunge (Jun 18, 2012)

hollo said:


> I'd argue more is better than less, if you have the capacity for more nitrifying bacteria, then in case you add more livestock or if there is an ammonia spike, the bacteria has a way of expanding and growing numbers.
> Also, from what I remember nitrifying bacteria _doesn't_ establish itself on plants? It's limited in the substrate due to the lack of oxygen in deeper levels, from what I remember as well.
> 
> Personally I prefer using biomedia for a good bacteria load, sponges both for bacteria and coarse mechanical filtration and then filter floss to filter out the finer things.


Well according to Jorge Vierke Nitrifiers are pretty much everywhere they can colonize in a tank. The better access to oxygen, the better for them to grow into large colonies. But they don't just limit themselves to filter media just because the flow is high.


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## Diana (Jan 14, 2010)

Optimum locations for nitrifying bacteria:
High oxygen
Ammonia
These 2 things require good water flow to refresh the oxygen and ammonia so the organisms will be on pretty much all the surfaces that otherwise suit them, including all the filter media, and on all the surfaces in the tank. I would think they could colonize the leaves and stems. Is there some research that says they do not?
Low or no light
So they won't be on the uppermost surface of the substrate, leaves or hardscape items, unless these surfaces are shaded by plants. The substrate often is, in a planted tank. They will grow on the underside of the particles, and in the next few layers, but as soon as the water movement slows, so there is less oxygen and ammonia, the bacteria population drops. Bacterial can grow throughout the substrate if you use an under gravel filter system. I understand aquatic plants can add oxygen to the substrate, so I would suppose these bacteria could grow next to or on the roots, if there is also ammonia. 

Benefits of bio media in the filter:
Very good benefit in a fish only tank. While these organisms will colonize all the media, in a fish only tank there needs to be a lot more bio filtration because there are no plants helping out. Sponges and floss can get clogged with debris, leading to lower water flow, so low oxygen. The bio media, being more open, will not clog so fast, and will still have some water movement, even if the water is following a path around the sponges. 
In a well cared for filter the sponges and other mechanical media will not get so badly clogged, but this means they are getting cleaned more often. This disrupts the bacteria some. Not much, though, and they recover fast. Still, having some media that is specially designed for optimum flow specifically for the nitrifying organisms, and the maximum surface area means that there will be a very large population of these organisms in the bio media. 

In a planted tank I see a lot less need for specific media just for the nitrifying bacteria. They will grow on most surfaces in the tank and filter, and there is less need for them, since the plants are part of the bio filter. 

I keep a small amount of bio media in my filters (perhaps 25% of the media is specifically designed for microorganisms). I use a lot of coarse and medium sponges, and some floss as mechanical. Depending on the tank I may add peat, coral sand, or other chemical media. The bacteria may colonize the coral sand, but I doubt there is much of a bacteria population in the peat moss. The floss and peat get replaced often enough that any bacteria that get established are soon lost.


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## PlantedRich (Jul 21, 2010)

Definition of bio-media is sometimes too restricted. Almost anything can be bio-media if bacteria can live on/in it. That includes sponges ceramic hard media and everything in between. The reason I see to include more of the things we would all call "bio" media is that it tends to be better at the job and in that way can let us stock much heavier. Almost everything we do needs to be adapted to best suit our situation. If we have lots of large fish and very little other stuff for taking care of ammonia, we may need to provide more "bio" media. If we had no fish, we might need none at all and simply let the plants use the pollution. 
Having large amounts of bio media gives me flexibility as it can harbor lots or little as it builds or declines without me dealing with the question. But then I don't go crazy and stock bio to the point that I'm short on mechanical, either.


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## RyRob (May 30, 2015)

We use biomedia to help establish enough nitrifying bacteria to breakdown the ammonia produced by fish waste and decomposing organics otherwise not being broke down by what natural nitrifying bacterial is in the tank (surfaces and substrate). Bio-load (waste AND decomposing organics) goes hand-in-hand with with nitrifying bacteria. Biomedia houses bacteria that converts toxins (ammonia) into safer compounds (nitrate) to help maintain environmental stability. That's why when we have an ammonia spike, it's a spike. It throws off the ballance of nitrifying bacteria because there isn't enough biomedia (surface area for nitrifying bacteria to colonize) to convert the excess ammonia into nitrite then nitrate. If we were to add more biomedia, it would eventually convert the excess ammonia but once all the excess was converted, you would begin to develop an excess amount of nitrifying bacteria again causing an imbalance (not enough "food" for the whole colony of NB) until enough bacteria died off to create the bioload/biomedia equilibrium. 

Nitrifying bacteria need to be fed just like everything else we put in our tanks and adding biomedia ensures a cozy cafeteria for that bacteria to settle in and pig out. For tanks that don't run additional biomedia (matrix, biomax, etc.) The sponges in the filter, or even the standard hob cartridge, become the biomedia. That's why it's important to rinse sponges and stuff in tank water instead of tap or ro/di/distilled, to help maintain as much beneficial bactiera as possible but declogging the sponges as best as we can.

Ammonia is fatal and can be physically brutal on fish if they don't die first. Adding biomedia helps us, as aquarium keppers, help maintain a healthy and balanced ecosystem for our tanks inhabitants beyond what is "natural" for the unique ecosystem. We just have the authority to determine what is "natural" for our unique ecosystems (bioload [plants and animals], dosing nutrients, injecting co2, controlling intensity and length of photo period, substrate choice, water volume/footprint/depth). All of which contribute to how well nitrifying bacteria establishes and where it establishes. Again, adding biomedia ensures a place for benificial bacteria to live and the amount of biomedia dictates how well it establishes relative to bioload. 

To echo hollo, I don't think you can have to much biomedia. I've seen serious goldfish keepers with 1 maybe 2 big fancy goldies in a 55g running a fluval fx5/6 solely for the filtration and biocapacity of the filter.


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## PlantedRich (Jul 21, 2010)

When I read this type of question it almost always brings me back to a basic thought. The folks who have been designing and building filters for so long do have a pretty good idea of what they are doing! 
So when I think I see a way to improve their design, I really have to ask myself if I really have a unique situation that I know enough to improve. Am I better at designing filters? Or is it the simple human fault of wanting to mess with a really good system? 
I try to restrain myself while answering those questions.


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## roadmaster (Nov 5, 2009)

I use a small amount of biomedia in canister filter's and it gives me some comfort that I can rinse out pad's /sponges at the sink that make up lion's share of media, without losing too much bacteria.
I also have largish plant mass and that too add's some comfort.


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## AndreyT (Apr 28, 2011)

Blackheart said:


> I never understood the point or need to use biomedia. I use HOB filters with nothing but sponges and have never had any issues with anything. That's just me though.


Er... But sponges *are* biomedia.


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## AndreyT (Apr 28, 2011)

chinaboy1021 said:


> Can somebody tell me why we put biomedia in our filters when the same nitrifying would establish itself in our substrate and plants otherwise? Also is there any benefits to having excessive biomedia


I'd argue that in the tank environment with relatively slow water circulation the efficiency of nitrifying bacteria would be relatively low. Yes, they would occupy every surface inside the tank (and they do), but the population of the beneficial bacteria would not grow pas certain limit simply because their food and oxygen would not arrive fast enough. I.e. the size of the colony would be _bottlenecked_ by the food/oxygen supply.

Inside the filter, where the surfaces occupied by the nitrifying bacteria are constantly subjected to rapidly flowing water, the bacteria experiences a significantly more _intensive_ income of readily available food and oxygen, which drastically expands the aforementined bottleneck. It expands it so much that food/oxygen is no longer a bottleneck at all. Inside the filter, the available surface becomes a bottleneck, which is why we tend to use various high-surface-area (porous) substrates for biological filtration.


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## loach guy (Jun 2, 2014)

The way I look at it is like this. Would you rather take a drink of water from a stagnant pond, or a fast flowing stream?


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## LionelC (Feb 27, 2014)

Bacteria will only grow and survive in numbers that the ammonia and waist can support. No matter what fancy super porous ceramic is in your filter, you will only have bacteria in a given amount that can be supported by the food available.


With an overstocked tank,(happens way too often) you may need the added media for the bacteria. But I think that a sponge is more than adequate for most planted tanks. Look at all the sponge filters and Hamburg Matten filters out there that only use sponges.


Just my opinion, but most of the "Super" medias out there are just sales gimmicks, unless you have 30 cichlids in a 55 gallon. 


LionelC


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## onlycrimson (Sep 7, 2010)

The only thing bio-media does is increase the surface area in which the bacteria can survive in order to have more of them to keep up with stocking load.

I've kept many tanks with no external filters and just power-heads moving water, but there was lots of surface area within the tank for bacteria. In my Koi pond there is no substrate and only the walls for surface area and very high stocking. In this situation i need a lot of bio media to keep up with the waste.


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## Boreas (Jan 24, 2016)

Using sponge filters and hamburg matten filters as an example of not needing "Bio media" is a fallacy. The flow rate in those two examples is slow enough that very little mechanical filtration is happening to clog the sponges pores. Therefore, the sponge becomes the "Bio media".

In a canister, I use sponges first to mechanically filter debris from the water coming through with a high flow. The bio media is next, it's designed to stay clean of debris so that the nitrifying bacteria can always have water flow available (Food source). The bio media being after the mechanical filtration makes the system more sustainable and efficient, in my opinion.

One of the "Bio media" trays in my canister is just leftover poret foam cut into cubes. I consider this bio media because I have set it up to stay clean and house nitrifying bacteria.

Is bio media necessary? Probably not. But is having it better? Yes.


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## AbbeysDad (Apr 13, 2016)

Interesting question in a planted tank forum! Pondering back to bio-filtration 101, I recall that ammonia is oxidized by nitrosomonas aerobic bacteria into nitrites and nitrites are oxidized into nitrates by aerobic nitrobacter bacteria. Now there are also anaerobic bacteria that can convert nitrates into nitrogen gas, but these are difficult to culture in the average FW aquarium (but is often employed with live rock and deep sand in SW).
HOWEVER, in a heavily planted tank, plants will use ammonia as a preferred food source which will limit the production of nitrites and nitrates...in the absence of ammonia, plants will process nitrates. So how much beneficial bacteria lives in the well planted aquarium becomes a pretty good question, with the logical answer being prolly only a little.
As to bio-media in any filter.... beneficial aerobic bacteria will attach to anything it can as long as there is sufficient oxygen and food. What better place than the filter that gets a constant supply of both fresh oxygenated water and food delivered 24/7! Still the size of the culture/community is dependent on ample food stock which may be somewhat limited in the well planted tank.

On the other hand, bio-media in the filter creates a potential staging area or buffer to handle nitrogenous compounds if/when they are present - so we might think of it like insurance...we don't want to use it, but if we need it, it's there.


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## Django (Jun 13, 2012)

I have been trying an experiment recently. I had removed the biomedia (wasn't that much of that) a while back, and recently I pulled the sponges, so there was no media in the filter. (Someone remarked in another thread that now I've got a powerhead like a Koralia).

My tank is a 10 gal., 2 10W CFLs for lighting, mediumly planted. I have 5 Pristella Tetras and 1 Panda cory. Even so, an online stocking calculator with the MTS in place (I entered 10) said I was above 90% stocked. The MTS all died recently, I don't know why. I don't mind that much because they were always having a population explosion.

The filter is a Fluval U2 internal. Water flow has to be above 5 volumes/hour and below 10.

So, the results: The fish have always done well - I've had them since 2012. There was a lot of particulate matter suspended in the water (maybe pieces of algae) immediately after. I just looked in the tank and the particulate stuff has settled and the water has cleared. So I well let it keep on going the way that it is. Now the closest thing I have to media is the plants.


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