Canister Filter Size + Bioload, Is Bigger Better?

[Alexp08]

So I want to talk about bio filtration. I see alot of people slapping massive filters on tanks with the concept of "more filtration is never a bad thing" but they then fill it with a whole bunch of bio media and little mechanical. Now I don't want this to get into a topic of the benefit of either mechanical or bio.
But rather the efficiency of strapping a large bio filter on a tank that it is very over rated for.

My thought. Bio media houses bacteria and micro organisms and such, and to make it simple they are fed off of fish waste.

So is it possible to have too much bio media. For instance if your bioload is not large enough to supply food to the organisms in the bio media then wouldn't it be wasted space? Space that could be better used for mechanical filtration?

Or am I missing a part of the equation?
Another thought I had was that the bio organisms also fed off themselves to anew extent. As some died the younger would feed off those. But once again thats only sustainable for so long.

It seems like a very fine equilibrium.

What are your guys thoughts?

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[eaglesaquarium]

It is an interesting question.
 
One thing to keep in mind regarding the extra space for bio-media.... bio-media is generally much more open and allows for better flow than mechanical filtration.  Mechanical filtration will slow the flow much more.  The idea of 'over-filtration' is to get more flow through the tank and 'turnover'. 
 
For example, in a planted tank you'd want to get about 10x the volume turned over every hour, in essence, every bit of the water will go through the filter every 6 minutes.  That's generally not how it works when a filter is rated to give you that.  Most of the ratings are based on the filter without media.  The media slows it down and the more the filter runs and builds up detritus and mulm the slower the overall flow.  Over-filtration helps to get the flow higher even as the filter slows down.  
 
Most canisters have specific set-ups for the media that you run.  Generally, I'd recommend removing the carbon media, which leaves some extra space, and the best option, IMHO, is to add more bio-media.  My canister has a coarse mechanical sponge, followed by bio-balls, then ceramics, then some finer mechanical media, finished off with a thinner 'polishing' pad before the water returns to the tank.  So, I have two mechanical sections and two biological sections.  I don't have any 'chemical' media.  Were I to need some, I would remove the second set of mechanical media and put carbon in there.  
 
 
That's my understanding of the thought process for over-filtration.  There are other thought processes, I'm sure.  But this would be my reasoning to do it.

 

[Akasha72]

when I bought my first JBL external (the e901) way back in 2012 there was two trays of ceramics (balls and noodles) and two trays of sponges. The theory was that dirty water passed through the small course sponges in the side before flowing to the bottom, through the ceramics and then finally through the two finer sponges and back into the tank.
 
Come forward to last year when I bought a second JBL e901 to run alongside the first one on my four foot tank and JBL had changed things a little. There is now only the bottom tray for ceramics and the other three are all sponge.
 
I don't know why this is but perhaps their research has shown the sponges to be better for bacteria than ceramics 

 
I will admit to not having all that much knowledge about these things which was why I thought I'd get involved in this conversation. Perhaps I can improve my knowledge

 

[AbbeysDad]

In reality the beneficial biology colony in any tank will grow....and shrink relative to the available living conditions of food and oxygen. And this has nothing to do with how much bio-media there is in any filter. In fact, the filter, although a good place to culture BB, but they will exist on any convenient surface in the tank.
 
I have long questioned the notion that we need 4x to 10x flow for filters and that "you can't have too much filtration". Nonsense! Good filtration is not about how many times you push water through a filter, but simply how well it's being filtered. The same is true for folks that add powerheads and such for more flow simply because a bit of mulm may appear somewhere in the tank.
Oh you want good water circulation in the tank, but it doesn't need to be a whirlpool!
 
I used to be a fan of 'fancy' bio-media (like Seachem's Matrix and DeNitrate) but I have come to the realization that bio-sponge material is in fact the best platform for beneficial bacteria in a filter. I use a coarse sponge to trap detritus, then finer sponge(s) to support bio-media, finally a layer of disposable filter floss to polish the water before returning to the tank.
 
footnote: By the way, bio balls are really made for drip systems in sumps and don't work very well submerged in canister filters.

 

[Byron]

I've been trying to figure out how to start my response on this issue...I think I will do so by following Michael's lead.  There is no benefit in using larger or more filters, if the system is biologically in balance.  It is actually possible to have too much "filtration," meaning the equipment not the biological process.  "Filter" can mean the equipment/machinery, but the term as "filtration" also means the biological processes that occur no matter what, provided we keep things in balance and don't do something to negatively impact those processes.  Nitrification for example--and this aspect of filtration is usually what most mean by biological filtration--will be present in the tank at the level necessary to deal with the nitrogen compounds.  It should and must also include denitrification, the rest of the process.  But once the aquarium has this filtration established, adding more filters is not going to have any benefit, but may be the opposite in terms of too much water movement.  The same must be kept in mind for the filter itself; if water is flowing through it too rapidly, the bacteria may be impeded.
 
I view the prime purpose of a filter to be mechanical filtration; as water passes through the media, particulate matter is filtered out.  Biological filtration will occur on this media, whatever it is, and I agree with Michael that sponge/foam type media does both mechanical and biological filtration the best.  This is why the old simple sponge filter connected to an air pump provided such superb filtration, and still does.  Biological filtration also occurs everywhere in the tank where all surfaces covered by water will form a bio-film, the places where all sorts of bacteria take up residence.  The substrate is in fact the most important "filter" area in any aquarium.  This is why the undergravel filters were so good; of course, that water flow can be increased to the point where this no longer functions as well, and it can become clogged.  But without the undergravel filter apparatus, the principle of water flowing through all that substrate, which it will naturally, results in a very healthy bio-system.
 
We need to keep in mind that a balanced aquarium can manage without any "equipment" filter at all, and the fish will be perfectly healthy.
 
Byron.

 

[Akasha72]

I run sponge filters on my fry tank and would agree that they do a fantastic job so that basicly has me questioning whether my externals really need the ceramics ...
 
As a side note - I only run the two filters because I found the one filter didn't have enough flow to clear the surface of a 3 1/2 foot tank (my old Rio 180) so there was no way it would cope on a larger 4ft. I also had dead spots with the one filter. Now I'm running two - one in each rear corner with the outlet nozzles pointed towards the middle front - the dead spot have gone and so has the greasy surface film

 

[NickAu]

 
I run sponge filters on my fry tank and would agree that they do a fantastic job so that basicly has me questioning whether my externals really need the ceramics ...

Same here, I am actually going to decommission the canister filter on my 2 foot Betta tank, I just can't see the point of using it with all the plants in my tank, I will just use the little sponge filter to provide a little current for the plants.

 

[eaglesaquarium]

Ceramics aren't 'necessary', but I find that they are very helpful.   First, they last, literally forever and as such provide a very economical option.  They never, ever need to be replaced, while all sponges eventually (though they last a long time) need to be replaced.  The ceramics also provide an easily transferable media to move from an established tank to seed a new tank.  Again, sponges could be moved as well, but I just find the ceramics to be far easier and less messy.  No cutting is necessarily, etc.
 
 
The need for flow depends on the species of fish you are keeping.  Obviously keeping bettas wouldn't require much in the way of flow, in fact, too much flow can be extremely dangerous.  But, if you are keeping loaches, like hill stream loaches, having more flow is far more important.  
 
Flow is also more important when it comes to plants in the tank.  Byron refers to 'balance', but that's required EVERYWHERE in the tank.  Having imbalance in a spot (a dead spot, as Akasha describes it) means that algae can take a foothold in that location.  Having sufficient flow to maintain the balance of nutrients and Carbon dioxide for the plants to grow and to allow the plants to outcompete algae is essential.  The amount of flow that is required to meet those needs is tank dependent, and I believe that this is one of the biggest factors in the individual character of every tank.  People will discuss how some of their tanks have algae issues, while they did the exact same thing in other tanks and never had an algae issue.  If the ingredients are the same, the inhabitants of the tank are the same, then something else must be the issue, and the one thing that is far less visible to our eyes to see as a problem is the flow.  

 

[hudsona85]

I posted a question in regards to a similar matter such as this conversation which are sump tanks. Not really got any answers from the post. I have a 20 gallon sump tank. Would this be considered overkill for a 90 gallon tank? I planned on using sponges since they worked for me in other tanks but at a larger volume to help support beneficial bacteria.


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