# Can you have too much bio filtration?



## BK-201 (Feb 9, 2016)

Just as the title says, wondering if there is a limit to how much bio filtration you can have in a tank and if there are negative effects if you have too much.


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## thedood (May 30, 2015)

Only if you are producing so much flow you are blowing everything in the tank around.


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## Maryland Guppy (Dec 6, 2014)

My vote would be no.

Reason: that enough BB will form to handle your bio-load.
As bio-load changes so will the quantity of beneficial bacteria.
Regardless of what they have to grow on.

Negative effects that may change water parameters would be mechanical.
Things like phosphate removal media or an Algae scrubber that would remove macros.
Carbon for copper med removal etc...
Purigen does not fall in this category it removes organics via resin.


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## BK-201 (Feb 9, 2016)

Maryland Guppy said:


> My vote would be no.
> 
> Reason: that enough BB will form to handle your bio-load.
> As bio-load changes so will the quantity of beneficial bacteria.
> ...



I'm running 2 biomax 20's in my 3 gallon tank and have an extra spot in my media rack for another one, I have some coarse sponge there rn so I was wondering.


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## Diana (Jan 14, 2010)

Bio filtration is the removal of toxins such as ammonia, via bacteria (ammonia -> nitrite -> nitrate) and via plants, which remove nitrogen in all 3 forms. It is also the removal of other things that we generally do not test for or list. Plants are good at this. In a planted tank there may be less nitrifying bacteria compared to a non-planted tank because the plants are removing a certain amount of the nitrogen. 

The microrganisms of the nitrogen cycle will only grow to the limits of their food (ammonia). 
If you add more of these microorganisms (lets say you dump in a large bottle of Dr. Tim's One and Only) than there is food, they will die off until they balance the food supply. In dying, they feed the ones that are still alive, so the population goes down slowly. It won't usually die off so fast as to cause an ammonia spike. 
So you cannot have too many of these microorganisms- they will die of starvation. 
You can add more and more plants into the system. Eventually the plants will be removing all the nitrogen and other things that they can (usually shown as a NO3 test of zero), and will be deficient in nutrients, and stop growing. You can add fertilizers to supplement them. 

The filter media that the micoorganisms prefer have lots of surface area, and the right pore size for good water movement. There are many species of microorganisms, not just the nitrifying species that live together in a complex web in a biofilm. Optimum water movement will bring oxygen and ammonia (and other foods) to the many species of microorganisms in the biofilm. These organisms will live on all the surfaces in the system that suit them. Optimum water flow, low light and so on. 
If you have too much filter media that is labeled 'bio media' then the organisms will only colonize the spots that are the very best, and only a few organisms will live on the areas that are less than optimum. Bio media is not generally very good at debris removal. 
If you have a lot of mixed filter media- sponges, floss and other things usually thought of as mechanical media, then the bacteria will colonize the areas they like whether you call it mechanical or bio. No matter how many microorganisms grow on these media, you are getting the benefit of both mechanical and bio filtration. 

Net comment:
If you have a lot of mechanical media, you are getting the benefit of the debris removal and the microorganisms. 
If you have a lot of bio media, you may not have enough mechanical media. It may be only partially colonized, too, since the plants are doing a lot of the bio filtration. 

So, lets reword the question:
Can you have too much bio media? 
Yes, especially in a planted tank where the plants are doing a lot of the bio filtration. The excess volume of bio media may take up the space in the filter that could be better used by more mechanical media. 

Can you have too much bio filtration organisms?
Microorganisms will die off to match the food supply, so no, you cannot have excess of these. 
Plants can grow only to the limits of their food, then may die, stop growing or look bad. They can crowd each other, shade each other and so on. If you are willing to take care of the plants, trimming, adding ferts as needed, and grow the ones that fit in the tank, then you cannot have too many plants.


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## dukydaf (Dec 27, 2004)

Well, depends on what we are talking about... If we are talking about biological filtration than no. Biological filtration would be bacteria that mainly transform NH4 to NO3. The amount of bacteria you will have depens on the amount of fish(NH4 sources you have). Plants will also compete for NH4. 

If we are talking about biological filtration media, it is the best way to reduce filter output  Reduced water flow can lead to problems in plant growth. Bacteria will grow in the substrate and on most surfaces not specifically in the biologcial filtration media. I see forums where biomedia is encouraged (reduce organic sources) or discouraged (increase flow rate).


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## BK-201 (Feb 9, 2016)

Diana said:


> Bio filtration is the removal of toxins such as ammonia, via bacteria (ammonia -> nitrite -> nitrate) and via plants, which remove nitrogen in all 3 forms. It is also the removal of other things that we generally do not test for or list. Plants are good at this. In a planted tank there may be less nitrifying bacteria compared to a non-planted tank because the plants are removing a certain amount of the nitrogen.
> 
> The microrganisms of the nitrogen cycle will only grow to the limits of their food (ammonia).
> If you add more of these microorganisms (lets say you dump in a large bottle of Dr. Tim's One and Only) than there is food, they will die off until they balance the food supply. In dying, they feed the ones that are still alive, so the population goes down slowly. It won't usually die off so fast as to cause an ammonia spike.
> ...


Thanks for such a detailed explanation! I learned quite a bit from you just now, so I believe I have enough mechanical filtration because the first media in my filter is polyester pillow batting followed by coarse sponge (I know my order is reversed but that just how it worked out with my mods). So I guess adding more bio media is pointless since I don't over feed the livestock and I have just the right amount of plants in my tank.


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## thedood (May 30, 2015)

BK-201 said:


> Thanks for such a detailed explanation! I learned quite a bit from you just now, so I believe I have enough mechanical filtration because the first media in my filter is polyester pillow batting followed by coarse sponge (I know my order is reversed but that just how it worked out with my mods). So I guess adding more bio media is pointless since I don't over feed the livestock and I have just the right amount of plants in my tank.


@Diana always gives excellent and thorough answers. She is a very knowledgeable member.


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## Immortal1 (Feb 18, 2015)

Diana said:


> Net comment:
> If you have a lot of mechanical media, you are getting the benefit of the debris removal and the microorganisms.
> If you have a lot of bio media, you may not have enough mechanical media. It may be only partially colonized, too, since the plants are doing a lot of the bio filtration.
> 
> ...


Given the above (Thank-You Diana!), which of the following would BB prefer to live in assuming I have an excess of each in my canister filter?


Typical plastic bio balls
Fluval BioMax ceramic media
Filter Floss
Course filter media
Smooth ceramic media
I ask this as I would like to remove one of the above and add more mechanical filtration.


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## dukydaf (Dec 27, 2004)

It is not preference, really all undisturbed surfaces will be colonised. Thus, media with large surface area has more bacteria. the largest surface to volume ratio is achieved in small spherical ceramic media. You can consider this as 'prefered'. It is what I use to seed aquariums. However, this media is also the one that reduces the flow so it is the first to go. 

In a low bioload with good filtration, another thing to consider is that the media that is first is more likely to have more bacteria than the last ( ammonia is already consumed) 

Sent from my HTC One using Tapatalk


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## Diana (Jan 14, 2010)

Typical plastic bio balls- not very much surface area compared to the volume they take up. Mostly empty space. Good in ponds with large filter volume so maximum debris passes through the balls without clogging. But with proper mechanical filter before the bio, these are not so good in an aquarium filter. I do not use these in aquarium filters. These would be first on my list of 'remove with care and make room for more useful things'. Could be useful in a sump, which has more volume to devote to different media. Be aware, though, that there may be quite a bit of bacteria on them, if they have been running a while. I would keep them in the system, perhaps hang them in a mesh bag on the side of the tank for a few weeks so the bacteria can grow elsewhere. 
Fluval BioMax ceramic media- high population, these are designed for maximum surface area and appropriate flow. Should use the right amounts of mechanical media before these, they will trap debris. I have some of these in each filter. Perhaps 25% of each filter volume is this or similar bio media. 
Filter Floss- I find this mats down over time and needs to be thrown away. I therefore suspect the flow through it is not consistent, may not grow so much bacteria. I use this as mechanical media, the last item before the bio media. I do not have much in the filter, and I do not see problems (mini cycle) when I throw away the old matted stuff and add new. Maybe 5% of the filter media is floss. 
Course filter media- Very important to have plenty to trap the debris, perhaps 50% of the filter volume is coarse sponge and medium-coarse material such as the blue and white bonded media. Lots of bacteria will live here, too. These materials hold their shape, and when regularly cleaned allow a good water flow. There is a lot of surface area on them, too. 
Smooth ceramic media- I do not see this as bacteria homes. IMO it does not do much to trap large debris, either (if that is what it is supposed to do). This would be the first item on my 'remove' list. 
The rest of the media in my filters is often chemical (peat moss for soft water tanks, coral sand for hard water tanks).


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