That has been my experience.
You can have a boatload of bio specific media, but will only have bacterial quantities large enough to consume the available food.
Same goes for where those colonies set up housekeeping.
Wherever the basic needs are filled the easiest , that is where your bacteria will grow the best.
Adding more media will not increase the size of a bacterial colony beyond the available food.
Like having a quart of drinking water.
Lining up a large number of glasses will not equate to more available water.
Let me be clear, I am not saying dump your bio media.
Certainly not for tanks that are not mature and stable.
During the first year, or so of a tanks life the bacteria are like infants.
Easily upset and require gentle care.
If you make it through the growing/stabilizing period you end up with a strong/healthy colony that can take quite a bit of abuse.
It also has the ability to expand and contract to the tanks load quickly.
With some tanks that could very well be in media set aside for bacterial growth, in others not.
I`m just sharing my experience, not trying to change anyones mind.
It was discussions like this thread that got me thinking, which led to actions that proved out, or disproved what was being discussed.
It`s all good..If you have healthy fish and a tank you have a hard time not watching..
Well, what more can you ask for.
What a great response!!! Straight-forward and no nonsense gobble-d-gook!!!
I (obviously) agree with KaiserSousay. I also tend to think that the topic of filtration is often over-analyzed. There is not so much science to this. It is just a matter of finding the right balance and maintenance routine. Admittedly, this is usually a unique personal journey that contains much trial and error. Unfortunately, the more $$$ that people have, the more they seem to believe they can "buy their way" towards getting the water quality they desire.
If the OP already has 24L of "established" bio media in cannisters, unless you have a persistent ammonia presence, it is doubtful that a wet-dry is going to provide any measurable benefit. The simplest, most cost-effective, and "MOST EFFECTIVE" measure for maintaining / achieving the desired water quality is to find the right schedule of performing water changes and cleaning your filters!!! This cannot be understated. Many people (for over 10 years, I was one of them), even with a good water change schedule, experience recurring nitrate issues (not ammonia) because they don't clean their filters often enough. No amount of water changes will compensate for this. Adding additional filters (including a wet-dry) will not compensate for this. Using "this", "that", or "the other" media will not compensate for this. It is "keep your filters cleaned, or else"!!! If you have gravel, as a substrate, the need to keep it clean is equally applicable.
More filters than required (look at KaiserSousay's "drinking water and glasses" analogy) only results in "more filters to keep clean". If you are 20-something years old, maybe you can pull this off. If you are 30-something (most likely with kids), it becomes more difficult. If you are 40-something (like me), you realize that "you've got better things to do". And, if you are +50, you couldn't do it if you wanted to.
Moral: Don't deploy more filters than necessary. Just keep the filters you have clean and do regular water changes and your water quality should be excellent.
