Fun with filters...

One of the more common questions we receive with regards to botanical-style aquariums is, "What kind of filters do you use in your tanks?"

It's a very good question, and one which has been on the minds of lots of hobbyists... Let's tackle it today!

Yeah, the ubiquitous, necessary, and highly important function of filtration in our aquariums is definitely something we, as lovers of leaves and botanicals, need to give a little thought to when we set up our systems. I mean, we DO have a lot of "stuff" in our tanks, don't we?

Of course, I could totally launch into a boring, been-there-done-that review on the various filtration types available in the hobby and what they do and... blah, blah, blah...However, you likely wouldn't read it and you'd be yawning the whole time. I mean, there's a 50/50 chance you might be anyways, but hey...

Yet, filtration is less than exciting to many of us. It's like a hobby "must have" that, once we figure out, gets little more thought. Yet, in the context of our botanical-style tanks, it IS fairly important.

Now, first- my "disclaimer" of sorts: I'm no filter "expert." I'm not an aquarium "gearhead."  In fact, I really don't care much for gear, really -much to the chagrin of many my reef keeping buddies. It neither excites me or stimulates ideas for me. When they launch into dicussions about why this light is better than that one, or how this controller can do this or that, my eyes start to glaze over and.... Yeah, you get the idea. I view filtration as something necessary to operate an aquarium.


Sounds like I'm the PERFECT guy to write a piece on filters, huh? My thoughts on this topic are based, like everything I write- on my personal experience and ideas, laced with a healthy dose of "opinions", dislike of gadgets, and plain old stubbornness... 🤔

So, here's the "long and the short" of this topic:

You can use just about any type of filter available on your botanical-style blackwater/brackish aquarium. The real considerations, IMHO, are: A) where in the water column you are bringing in water, and b) Where the outputs are aimed. Oh, and C) what media you're using in the filter.

So, let's look a bit closer at this stuff. 

I have used all sorts of filter systems on my BWBS style systems over the years, but the ones that I tend to use most often will probably surprise you...maybe. Maybe not.

As a reefer, I love my tanks with built in overflows and sumps.

(My friend Marc Levenson makes all sorts of badass sumps, look him up.)

I love sumps. I love them because:

a) You don't see any of the ugly shit (heaters, etc.) in the tank proper. Oh, and even that freakin' "glassware"- yes, I know that YOU may not think they're ugly, but I"m no fan of them as they are now. They completely and utterly suck in every way, in my humble opinion. I hate them. Why? We can have that discussion some other time, okay?

b) Sumps add water volume to your tank. As the sayings goes, "Dilution is the solution to pollution"- and stability! So, that's always a good thing!

c) Sumps provide an area where you can keep filter media, biological media, botanicals, wood, etc. to influence environmental conditions in the display aquarium. Like, if you hate the look of leaves and decomposing stuff in your display, but love the blackwater look and biodiversity, sumps are a good choice. No, a great choice!

d) They rely on surface overflow "weirs" to supply water. Overflow weirs skim water from the surface, removing the film which accumulates and can interfere with gas exchange...Important when you have lots of botanicals in your tank breaking down, right?

Now, I realize that not everyone wants the expense, logistics, challenges, and additional considerations (return pumps, space under the tank, etc.) which go along with the use of sumps. I also realize that the majority of freshwater hobbyists utilize glass aquariums without overflows and such, so there are numerous other options.

Enter the "All-in-One" tank.

"All-in-one" tanks, like my Innovative Marine "Fusion Lagoon" system, or my Ultum Nature Systems AIOs, offer a great "hybrid" of a sump and an external filter, making an affordable, simple, aesthetically clean, easy-to-maintain-and-operate system.

Like with sumps, AIO's keep the ugly stuff out of the display proper, give you plenty room for media, and some additional water volume. The downside is that, even the best of them typically have inferior quality pumps (ie; noisy), so you'll likely want to "retrofit" them with better quality pumps your choice.

I really think that AIO's are a cool alternative to all of that external stuff. They ARE bit pricier, and you're limited to the shapes and sizes which manufacturers offer, however.
What are the alternatives? There are plenty, right?
Of course there are!


Enter the canister filters!

Where would the hobby be without Eheims, Fluvals, and all the other canisters out there? These are wonderful choices because they provide you so much flexibility. 

Flexibility is really important in what we do.

As is the ability to hide the "visuals" of ugly canister filters for obsessive types like me...there are plenty of approaches you could take.

And of course, they offer "functional flexibility"...You can keep botanicals, like various leaves, cones, catappa bark, "Fundo Tropical", etc.  in filter media bags/cartridges, again giving those of you who like the tinted water but not the botanicals and their associated decomposition, biofilms, and detritus- the ability to keep them outside of the display proper. 

Oh, and where the water comes back into the tank is pretty important, too!

IMHO, you should direct the return from canister filters near the surface, to create agitation and to facilitate gas exchange. Unlike pure planted aquariums, where there is a definite benefit from using those $&%#@@ "Lily Pipes" and such to return water well below the surface to preserve CO2, I personally believe that heavily-stocked botanical-style aquariums benefit from this surface agitation.

Did I mention that I hate those pipes? Just wanted to make sure.

I mean, you can return some of the water towards the lower levels of the tank to keep things "stirred up" just a bit, without blowing shit all over the tank. (that's a technical term, by the way).

And of course, outside power filters do the same thing- keep everything relatively neat and tidy, and potentially outside of the tank if you like. I think they're kind of ugly to look at, though, particularly in smaller tanks.

Oh, and sponge filters are great- and those Matten Filters, too- because they are primarily biological filters and are relatively easy to hide in displays...

Now, I have spent a fair amount of time over the years alleviating the fears of you weirdos who don't want to see leaves and pods and such in your tank physically by explaining that you can just toss these things into your filter or sump! We've even come up with our botanical "tinting sachets", called "Shade", just for you! And we have two new "flavors" coming in the next few weeks!

And of course, it goes without saying that you can utilize all of these filters with the botanicals present in the display, as well, of course.

Like, duh.

The real "issue", if you want to call it that- with filtration in regards to our BW/BS-style aquariums is what media you utilize. Again, I call on my reef-keeping experience to tell you that I am a huge fan of activated carbon. I use it on every tank I set up- even the ones with the gnarliest (yes, it's a word- I'm from L.A.-we talk that way. It's a word. Deal with it.), darkest "tint"  imaginable. 

I love activated carbon.

Yes, carbon can remove some of the tint and probably even some of the valued humic substances and other beneficial compounds exuded by botanicals. It's not selective. That being said, it also can remove impurities, like volatile dissolved organic compounds, urea, some metals, etc. It's valuable stuff.

The key is to just not overdo it. Of course, if you want leaves and such in your tank, but not the tint- as we've discussed many times- just use the 'typical" dose of carbon and you have the best of both worlds- at least, aesthetically.

Better as chemical filtration media would be stuff like specialized ion-exchnage or "organic scavenger resins" and zeolites- stuff which requires more research, trial and error, and testing. But it is possible, at least in theory, to incorporate filtration media which removes the undesirable pollutants and retains the desired humic substances and tannins. Oh, and proper biological function in low pH systems, fostering the "biome" of these tanks.

I like the"Poly Filter" pad, by Poly BioMarine, as it removes organics and can remove stuff like ammonia even in low pH systems. In my years of working with this stuff, I have not seen it remove substantial amounts of the "tint" in the water caused by tannins from botanicals. This is hardly a scientific assessment of the stuff, but I believe in it. I've used it for decades in pretty much every type of aquarium- fresh, brackish, reef- that I've maintained with excellent results. 

And back to those "specialized resins" and such...

These things are are all something we will see more of in the me. There are numerous materials out there, used in other water purification work , that will definitely work with our aquariums.

In the mean time, you can continue use materials like carbon, Purigen, etc. to do the trick; just be aware of the way they work and what they will do. If you go "full power" (ie; the typical manufacturers' recommended "dose"), you'll have a really clear tank- if that's what you want.

Nonetheless, I adore Seachem Purigen.

It's a "macro-porous synthetic polymer" (aka "organic scavenging resin") that removes soluble and insoluble impurities from water by adsorption. In other words, it cleans up stuff.

Like, really well.

I think every aquarist should have Purigen in their "box of fish stuff...not just for regular use, but for...well...emergencies and stuff. It's really good stuff.

And of course, we recommend mechanical filtration media, like plastic "noodles", filter pads, floss, etc., and of course, biological media, too- you know, the ceramic beads and such.

And no, I didn't even touch on how to optimize the placement and utilization of filter media in your filter, etc. That  stuff has been written about for many years by people who are way more interested and knowledgable about it than I am. Don't be lazy- Google it, if you're so inclined.

In summary- my advice is to use whatever type of filter system you like. The key is how you utilize it- what media you employ, where you draw the tank water into it, and where it's returned.

And, like with everything else we play with in this arena, there is plenty of room for experimentation, innovation, and even breakthroughs in regards to filtration in our BWBS systems. 

As you know, we place a real "premium" on biological "filtration" and the cultivation of a"biome" of organisms to support the aquarium's ecology. By having large quantity of botanical materials, and fostering the growth and development of this community of organisms in your tanks, you could, in theory, have no supplemental filtration system.

Yeah, you could use no filter, or just aeration, or even just employing a surface skimmer- and no other filter. The skimmer would facilitate gas exchange and provide some aeration.

Now, you would have to obey the fundamental principles of aquarium management...water exchanges, proper stocking, careful feeding, etc. However, you can do this; I've done it many times.

We've especially done this with the "Urban Igapo" type of tanks, which rely on the biotia in the tank as a result of the substrate, vegetation, and botanicals. It's a throwback, if you will, to the earliest days of the aquarium hobby, when process and active management performed many of the same functions as filtration does today.


When we consider the aquarium itself as a living, breathing entity- one which has levels of life forms performing the biological filtration function, such bold experiments and concepts aren't all that weird, right?

This is a real "open source" component of what we do. An invitation and opportunity for YOU- the working aquarist- to make a big impact on the hobby, fostering benefits perhaps as yet not understood...

Is there one "best" filtration method?

Of course not.

So, yeah- use what works for you, benefits your fishes, and creates the best outcomes for them. There are so many approaches, any of which could work for you. 

The concept of filtration is constantly evolving. To me, besides the obvious benefits of utilizing media which can remove impurities and organics on a continuous basis from the aquarium, the most important ones are circulation and gas exchange/aeration.

So, my thinking has been that you could actually use the tank itself and the botanical environment as the"biological filter", and simply use aeration/surface skimming and/or circulation pumps to facilitate the gas exchange. Not revolutionary, of course- but an idea that's often overlooked today.

Lots of potential experiments await the creative fish geek!

Stay excited. Stay engaged. Stay bold. Stay curious. Stay inquisitive. Stay innovative. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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