How Important Is Bio Media?

[Jgray152]

Sort of interested but at the same time, I think this thread will eventually come to a closure pointing out why you need bio-media or at least some sort of media.

Media in a filter, doesn't matter what type, is a safe haven for the aerobic bacteria to thrive considering in theory the bio media should never be touched which as everything else in the tank will be as well as the sponges in the filters.

You could use plain gravel as bio media in a filter and probably do fine. Rougher media may help bacteria to colonize without "slipping" away with the very high velocity flow moving through the media. I am sure the rough media will also cause friction and small vortexes in the water column which may help with the transfer of toxins as well. Just a theory though.

"Bio Media" specifically I do believe is over marketed. But the use of some sort of media to house bacteria in a safe haven such as you filter will provide more security to your biological system.

Also, this goes to all that add WAAAAAYYYY to much bio media to their system and think they need more. Also to those who suggest large volume amounts of media for specific sized tanks.......don't get me started. please.

Look at the fx5 compared to the Eheim 2180. One can go maybe 2 months between cleaning and the Ehiem 6-8 mo. This may also be due to canister size also. If you only have a sponge or two in a heavily stocked tank you run the risk of it clogging fast and nitrities/ ammonia spiking IMO.

You have to look at the cross section surface area you have available for your mechanical filtration. The Fx5 without sponges in the center will not clog up for an entire year i'm sure where as the Eheim will. If you use the center sponges, the cross section surface area is drastically reduced, not good when in combination of fine filter pads.

 

[hybridtheoryd16]

This is not true. Ordinary atmospheric air has much higher concentrations of both CO2 and O2 than water can hold, even at saturation. These gases will tend to diffuse down the concentration gradient, into the water. Agitation, trickling, etc. increase the rate of diffusion by increasing the water/air contact area and by breaking up the gas-rich surface layer which tends to form in still water. So these methods increase the amount of oxygen and CO2 in the water.

More importantly, and as nc_nutcase already mentioned, the bacteria in a trickle filter can carry on gas exchange directly with the atmosphere (so long as they stay wet). So they have access to far more O2 than submerged bacteria do and so can metabolize ammonia and nitrites more quickly.

NC_nutcase, I see your point but I think your wording is a little misleading. Bio media is crucial, but bio media covers a broader range of materials than the suppliers would have you believe.

In all my research it has said that the bacteria that we refer to as beneficial are purely aquatic. And they get there food source from the water as well.

I wish i could find the article to reference but I can't.

 

[Noto]

The "beneficial" bacteria are not purely aquatic; the very same species may be found in and on soil and various other surfaces. In fact, it is possible to "instantly cycle" a tank with soil, though that is a topic for another thread. These bacteria require moisture, but do not necessarily need to be submerged. They also require food (nitrogenous waste), oxygen, and a place to attach themselves. A trickle or "wet-dry" filter is designed to provide all these things in abundance. Submersed media also provides these, but is less effective at providing oxygen; so, if oxygen is the limiting factor in your bacteria's growth, emersed media will be more effective for you.

 

[BPags52]

How do you feel about bio-wheels?

 

[Pharaoh]

In reality I would suggest a liter of Bio Rings offer no more usable surface area than a liter sized Aqua Clear sponge…

I think this is an interesting discussion altogether and you make a very valid point. My only thought is to not confuse need with the potential of a substance to harbor BB. All I am saying, is that the two types of media may prove to be adequate in one setup, but there is most likely and difference in the surface area and at some point one would prove to be a bit more effective than the other. But the when looking at the argument as a whole, you are correct. I'm just being picky. LOL

 

[Noto]

How do you feel about bio-wheels?

I've never had one that worked properly. I think the idea is sound.

 

[brianp]

There were some additional points made that I felt I could clarify a bit, based upon my understanding of these processes.

Are we being misled by claims of theoretical surface areas?
If we had a biofilter particle which was permeated with fine pores running from one side of the particle to the other, then including the surface area provided by these pores could be misleading. The reason for this is, as previously stated, water will not flow into these pores AND, more importantly, diffusion is not sufficient to drive oxygen, ammonia, etc., efficiently into these pores (if they exceed a certain length). The exception would be a case where let’s say we had a particle which was 4 mm in diameter. This means that the longest distance that a substance has to be pushed via diffusion is only 2 mm and I believe this is well within the reach of this motive force. Unfortunately, 4 mm diameter particles would pack much too tightly and would impede water flow through the particle bed. I think that the most of the biofilter particle types constructed from either ceramic or sintered quartz do not have pores running their entire length. Rather, I believe they rely upon shallow pores, furrows or surface irregularities to dramatically increase the particle’s surface area. As water moves across the surface of these particles, there is a two-way exchange of oxygen/carbon dioxide, ammonia/nitrite/nitrate, etc., via diffusion. Sort of like two lines of people moving past one another on the up and down escalators and exchanging merchandise as they pass one another.

Does the use of bioballs in a wet-dry mean that practitioners have decided that large surface areas are not required?
I don’t think so because they attempt to compensate for the decreased sa of bioballs by expanding the bed volume. This is why bioball beds (usually in sumps) are so large compared to the bioparticle beds in canister filters. With biofiltration, you need to provide surface area and oxygenation. It seems that wd practitioners emphasize oxygenation as their parameter of choice to achieve nitrogenous waste oxidation, while canister filter fans think surface area is a bigger deal. Obviously, they both achieve the same objective but with a somewhat different mechanistic approach. Frankly, I don’t know which, if either, is actually more efficient…all factors considered.


Bacteria grow on a variety of surfaces in the tank.
This is true, but IMO the real objective should be to promote and optimizing the diffusive exchange of metabolites that is occurring between water moving through the filter and the particle surface.

Let’s think of a single ammonia molecule entering the filter. In order for this molecule to be oxidized to nitrite it has to move from Point A…to…Point B. Point A is the water within the spaces between the media particles in the biofilter bed. Point B is the surface of the bacterium that will consume this molecule.

Here are the facts:
1. Diffusion is the only significant force driving the ammonia molecule to move from Point A…to…Point B.
2. Diffusion of any molecule is dependent upon two factors:
a. Temperature and
b. Steepness of the concentration gradient between Points A and B.
3. In an aquarium, water temperature is irrelevant because it is set with respect to the requirements of the fish.

Here are the implications:
1. To establish a steep ammonia concentration gradient, we have to establish a high concentration of ammonia at Point A and a low concentration at Point B. This means that there has to be a continuous delivery of ammonia to the biofilter, coupled with a continuous uptake of ammonia by the bacteria.
2. Brisk water flow will maintain a high incoming concentration of ammonia within the biofilter bed (Point A).
3. Brisk water flow will deliver oxygen to the bacteria (Point B), supercharging their metabolic activity and uptake of ammonia. This will prevent ammonia from piling up at the bacterial surface and will maintain a low ammonia concentration at Point B.

All of the above is another way of saying that the nitrogen cycle will occur in gravel, inside tubing, on the glass panels, etc. However, to really have the oxidation of waste humming inside your aquarium, you need the brisk flow of oxygenated water over the surface of particles with a high surface area. Don’t forget, an aquarium is NOT essentially a small lake. It is a VERY SMALL, closed system, often with a dense population, that is supported by various technologies and the constant input of energy (electricity). So, passive measures, such as relying upon the nitrogen cycle occurring in the gravel are usually not sufficient.

 

[BPags52]

I've never had one that worked properly. I think the idea is sound.

What didn't work properly? and what brand filter was it?

I've been using 2 Emperor 400s for 5 years now, and they still have the original bio-wheels they came with, and work just fine.

 

[Toby_H]

Quoted from Seachem’s website here - http://www.seachem.com/Products/product_pages/Matrix.html

Each liter of Matrix™ provides as much surface (>~700 m2) as 170 liters of plastic balls!

1 liter is 61 cubic inches…
700 square meters is 1, 085, 002 square inches…

So that’s 17,787 square inches of surface area per cubic inch…
Compared to the claim of 104 square inches per cubic inch with bio balls…

I am very confident in my claim that Seachem’s Martix does not have 17,787 square inches of surface area per cubic inch that is readily available for bacteria to grow on and engage in a chemical exchange with our water…

I think the over viewing the above details makes the obvious answer to this question… Yes, we being misled by claims of theoretical surface areas… or at least those of us who believe the media manufacturers are…



In addition to being mislead there… Based on ample personal experience with fairly heavy stock loads… in aquariums with ample water movement… yet with no “Bio Media” (meaning specialized media for housing bacteria)… typical levels of décor (décor supplies surface area)… and simple sponge media…

Once mature, I find such systems to maintain zero ammonia & zero nitrites while building nitrates… with no measurable spikes… provided stocking is kept consistent…

Which has lead me to believe that with proper water movement in the system, far fewer square inches of bacteria are actually required/used in keeping our ammonia * nitrite in check…

 

[Freezekougra]

How do you feel about bio-wheels?

I would like to know this too.

I have 4 biowheels from the filters that came with my used tank. Would floating enough biowheels(or some other kind of biomedia) with an air pump to move water be adequate for a tank?