Filter Theory

[LakeyGal]

I have been wondering randomly about filters...

In my main (180l) tank I have a (fluval 305) cannister filter matured & running effectively with approx 25-30 inches of (fairly messy) fish...(I also have an internal in there but that's more for backup))

Would removing a number of these fish change the levels of bacteria in the filter or would they stay at the same level and just suddenly become more efficeint for the remaining fish.

And does having a second filter affect the levels of bacteria in filter 1 or are they separate entities...i.e if you have 2 filters and remove one will the remaining one struggle to catch up even if it is the right size to be alone anyway?

No urgency to the question but the more into the hobby I get the more things I begin to ponder on....and it's never a google type question!!

Any opinions / theories ??

 

[jarcher1390]

Might help with tank size, fish, and what filters have you got running on it

 

[vic]

I would think that the bacteria level in the tank would be in direct relationship to the availability of food for the bacteria colony. A reduction in fish waste will likely result in a reduction in the "size" of the bacteria colony within the tank, and vice versa. That would lend some credence to the don't increase the bio-load too quickly as it my trigger a spike as the bio-filter does not have the capacity to deal with the suddenly increased mass of bio-waste. Through put of the bio-filter is subject to the capacity of the bio-filter at any particular level/size. An increased bio-load may be beyond the capacity of the existing bio-filter.
Vic

 

[Aphotic Phoenix]

Bacteria are living organisms and thus just like populations of larger animals, the bacterial population will fluctuate depending on the amount of food readily available.

 

[LakeyGal]

Certainly sounds logical that they share the food......theoretically if I was moving some fish out but wanted to keep high levels of bacteria so replacing them with others wouldn't affect the bioload would overfeeding maintain those levels

 

[Don Trinko]

The best way when you are increasing the bioload is to increase it gradualy. You can increase it more but you will probably have an amonnia and/or a nitrite spike. These can be taken care of with chemicals or water changes. Don T.

 

[Bignose]

Just like all organisms, bacteria need a certain amount of food to live. If you decreased the amount of food, ammonia in this case, some of the bacteria are going to die. It is as simple as that. The size of the bacterial colony is in equilibrium with the rate of ammonia production. The bacteria colony will grow to the size so that the colony's rate of ammonia uptake is exactly the same as the rate the fish produce ammonia. Well, if you reduce the rate ammonia is produced, by removing fish, the colony will shrink until it's ammonia uptake rate is the same as the new production rate. Exact same way, if you add fish, thereby increasing the ammonia production rate, the colony will grow until its ammonia uptake rate is the same as the new production.

Once you have a sizable established colony, additions aren't so bad. The total number of bacteria have the potential to double about every 24 hours or so. What this means in practical terms is that the addition of 2 fish to an established tank of 40 fish probably wouldn't even be noticed. However, the addition of 2 fish to a tank that was established with only 2 fish would experience a mini-cycle as the bacteria catch up. Of course, it does matter what 2 fish we are talking about, but these is in general terms only, here.

 

[rdd1952]

I agree with Bignose. I will touch on another question you asked about 2 filters. They are seperate entities but should have a colony of bacteria, once again, in direct proportion to the amount of food brought through the filter. So for instance, if you have 2 filters both rate the same gph, then the two filters should have roughly about the same amount of bacteria present, assuming they are both performing as they should. If however, one of your filters is rated say 100gph and the other is 200gph, then the higher rated filter should have about twice as much bacteria in it since it is processing twice as much water and food.

Removing a filter does indeed effect the bacteria. As Bignose mentioned, the bacteria would have to start reproducing until their quantity was large enough to handle the waste again. In the case of the two identical filters, it should only take about 24 hours for the bacteria in the single filter to multiply enough to handle all the waste. In the case of the two different filters, removing the 200gph filter would mean that the other filter would require more time to catch up as you have removed approximately 2/3s of the bacteria.

You also mentioned efficiency. From what I have read, that is something that comes into effect. I have read at least 2 articles (which I would have to find if someone wanted to see them) that stated that the bacteria colony would become more efficient over time so that the quantity of bacteria initially needed to process the waste of say 20 tetras would actually decrease over time as the colony became more efficient at processing the waste.

 

[Danno]

Seeing that bacteria colonies have a potential to double in size every 24 hours, would it be possible to start new colonies in that same amount of time, seeing of course that you add new places to colonise? I guess that wasn't a very good explaination...

One filter running a sponge in a cycled tank.
Add another filter in with a sponge in the same tank.
Both sponges equalize?

I wonder if the initial colonising time would take longer...

Gives me an idea to farm bacteria

 

[rdd1952]

They would eventually equalize but it will take some time. It won't happen in 24 hours though as the bacteria first have to start building on the new filter and then begin to multiple. How long it will tank is hard to say. And keep in mind that the number of bacteria in the tank isn't going to increase because you added a second filter. It will just be moved around. There will never be more bacteria in the tank than what is needed to process the bioload present.

There'a actually no need to "farm" bacteria. All you have to do to start another tank is remove some media from the existing filter, replace it with new media and put the seed media in the new filter. You have an instant bacteria colony to start cycling a new tank.

 

[LakeyGal]

And keep in mind that the number of bacteria in the tank isn't going to increase because you added a second filter. It will just be moved around. There will never be more bacteria in the tank than what is needed to process the bioload present..

So theoretically providing you start with a capable filter is there actually no benefit to running 2 filters with similar media as the bacteria is shared....would you suggest that if someone sees an improvement when adding a second filter that means the first wasn't up to the job to begin with


Incidentally thanks for all the input so far...

 

[andywg]

So theoretically providing you start with a capable filter is there actually no benefit to running 2 filters with similar media as the bacteria is shared....would you suggest that if someone sees an improvement when adding a second filter that means the first wasn't up to the job to begin with


Incidentally thanks for all the input so far...

How do you "see" an improvement in bacteria levels?

Most people see an improvement because the second filter does a better job of mechanical filtration, thus causing less particles to be seen in the tank.

 

[LakeyGal]

How do you "see" an improvement in bacteria levels?

smartypants

I just meant if there was changes in the tank visual or not...

 

[LukeFishwalker]

You also mentioned efficiency. From what I have read, that is something that comes into effect. I have read at least 2 articles (which I would have to find if someone wanted to see them) that stated that the bacteria colony would become more efficient over time so that the quantity of bacteria initially needed to process the waste of say 20 tetras would actually decrease over time as the colony became more efficient at processing the waste.

Not to be too much trouble but I would like to read some of those articles. I dont need the exact link - just point me in the direction of the journals and I'll be set.

 

[LakeyGal]

muchas gracias