Second filter added... when will it be at maximum filtration?

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blairan

Aquarium Advice Apprentice
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Jan 2, 2011
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Baltimore, MD
Hey all!

I recently added a second filter (Fluval Internal U3) to my existing set-up (65 gallon with Aquaclear 70). In less than 24 hours I am already noticing significant improvement in water clarity. I am wondering how long it will be before I can assume I'm getting the maximum biological filtration benefit from the new filter?
 
Think of it as if you're cycling the tank. Both have to build up the bacteria, just the tank is a larger space. It can take roughly the same amount of time, 3-6 weeks.

Since your tank is already cycled (judging by you stating it's an existing set-up) it shouldn't take much longer than 3 weeks. But, there's no exact timing to this either. :)
 
What you have to consider is that if your tank was already cycled before you added that new filter, you're not going to have any more beneficial bacteria than before. The nitrifying bacteria require ammonia and nitrites to live. Once the tank has cycled, they will have established a big enough colony to cope with that bio-load. If you add more fish, more bacteria will come about. If you take some of the fish out, you'll have less bacteria.

Essentially, all you've done is add extra mechanical (and potentially chemical) filtration to the tank.
 
I see... interesting! So in order to increase biological filtration I have to change something in the tank (like the number of fish) in order to increase the ammonia and nitrites available to support additional bacteria? That makes sense.
 
What you have to consider is that if your tank was already cycled before you added that new filter, you're not going to have any more beneficial bacteria than before. The nitrifying bacteria require ammonia and nitrites to live. Once the tank has cycled, they will have established a big enough colony to cope with that bio-load. If you add more fish, more bacteria will come about. If you take some of the fish out, you'll have less bacteria.

Essentially, all you've done is add extra mechanical (and potentially chemical) filtration to the tank.

I have a slightly different view of this (and its JMO), while it is certainly true that the total amount of nitrifying bacteria living in your tank is dependant on the food source so to have a bigger colony you would need more fish, adding the second filter means that now your total bacteria population will be distributed between your 2 filters and I would argue that your biological filtration is increased in that there is now more water running through your filters at any given time. In short your ammonia and nitrite clearance rate should be increased.
 
Think of it as if you're cycling the tank. Both have to build up the bacteria, just the tank is a larger space. It can take roughly the same amount of time, 3-6 weeks.

Since your tank is already cycled (judging by you stating it's an existing set-up) it shouldn't take much longer than 3 weeks. But, there's no exact timing to this either. :)

If you were to put a piece of media from the old filter inside the new one, the new filter would be colonized in a matter of days rather than weeks.

I have a slightly different view of this (and its JMO), while it is certainly true that the total amount of nitrifying bacteria living in your tank is dependant on the food source so to have a bigger colony you would need more fish, adding the second filter means that now your total bacteria population will be distributed between your 2 filters and I would argue that your biological filtration is increased in that there is now more water running through your filters at any given time. In short your ammonia and nitrite clearance rate should be increased.

I agree with this. Having more media means the colony can spread out. Spreading out = room for growth. When a filter isn't big enough to handle a bioload, it is because there isn't enough surface area to hold enough bacteria to process it.
 
So if I'm understanding you guys correctly, the increased gph of the combined filters, as well as increased surface area provided by the second filter should improve ammonia and nitrite conversion?

I also wonder if mfdrookie's point, that increasing the bioload in the tank, would have the effect of increasing the "value added" of the second filter by providing more food for nitrifying bacteria thereby giving filter #2 more to work with?
 
I'm not saying they're wrong, I'm just summing up what I've read while researching the nitrogen cycle, nitrifying bacteria, etc. I can understand the point about running more water through, but at the same time, that conflicts with a lot of research I've read.

Even though I may have contradicted what your goal is, the second filter will definitely be an excellent addition to your tank. If nothing else, you're providing more mechanical filtration, which is always a good thing.
 
If you were to put a piece of media from the old filter inside the new one, the new filter would be colonized in a matter of days rather than weeks.


Yes, assuming that is the way the poster wants to go. Not all filters have room for you to stick a piece of media from another filter in them. I know with a few of my HOBs there's no way to get anything in there unless I take out the filter pad and move it to the other filter. Where as with my Fluvals I can take out some ceramics and move them to another Fluval or even use filter pads from my HOBs.
 
Hello to everyone at Aquarium Advice!

Assuming the poster's aquarium has been properly cycled and is in balance before the U3 was added, then all the new filter will do is share the bioload of the aquarium and process the ammonia, nitrite, nitrate faster. In other words a portion of the bacteria in the 1st filter will migrate to the 2nd filter and distribute the bio filtration. In that case, the filters will not be working at their max in bio filtration, and you would have the option to increase the bioload by adding more fish, just be aware you will need to make bigger/more frequent water changes. <= reiterating, mfdrookie's point and XimeD's point as i understand both are correct
However if the bio load of the aquarium is MORE than the old filter could handle, that is there is no balance in the aquarium ie. it is underfiltered, then a NEW colony will appear in the 2nd filter to pick up the slack.
If you want to colonize the U3 faster, cut a small slit the aquaclear's bio pouch which you can mend with some thin fishing line and put some of the ceramic rings out of your aquaclear into the U3.
 
So if I'm understanding you guys correctly, the increased gph of the combined filters, as well as increased surface area provided by the second filter should improve ammonia and nitrite conversion?

I also wonder if mfdrookie's point, that increasing the bioload in the tank, would have the effect of increasing the "value added" of the second filter by providing more food for nitrifying bacteria thereby giving filter #2 more to work with?

You don't gain more bacteria by running a second filter. There is only ever 100% when it comes to beneficial bacteria. So, there's say 10% in the substrate, 10% on decor, and 80% in the filter for a total of 100% By adding a second filter (lets say it's identical to the first), the 80% is split in half, so now it's 10 in the substrate, 10 on the decor, and 40 in each filter. Lowering the percentage in the filter allows for greater growth of the colony. The ONLY way to grow the colony is to have an excess of ammonia (increasing the bioload). The extra GPH is beneficial because it feeds the bacteria faster. The single filter setup is going to run closer to maximum capacity, so there is a risk that the BB colony will be overtaxed and not have room to grow to make up the difference. A 2 filter setup will mean that each filter is running at a lower capacity (half the bioload of the single filter), allowing for plenty of room for growth.

As the bacteria colony in the new filter grows, the colony in the old filter starves. This continues until they reach an equilibrium.

If you were to put a piece of media from the old filter inside the new one, the new filter would be colonized in a matter of days rather than weeks.


Yes, assuming that is the way the poster wants to go. Not all filters have room for you to stick a piece of media from another filter in them. I know with a few of my HOBs there's no way to get anything in there unless I take out the filter pad and move it to the other filter. Where as with my Fluvals I can take out some ceramics and move them to another Fluval or even use filter pads from my HOBs.

Even a clipping from the edge of a cartridge will do the job - as long as you are transferring an established colony, it will colonize the new media quickly.



Good post vialznk :)
 
Thanks to everyone who provided their input and information... I think I'm starting to understand how the bacteria colonies in my filters work!
 
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