We spend a great deal of time contemplating the look and feel of our botanical-syle aquariums, and wrapping our head around the various "mental shifts" necessary to really appreciate and embrace this approach...You know, learning not to fear the tinted water, decomposing botanical materials, biofilm, detritus, etc.
And that's really great. It's foundational.
However, one of the things we don't talk about as much as we should here is actually another foundational aspect of our aquarium practice: filtration.
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.
Of course, I could 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 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...
Now, first- my "disclaimer" of sorts: I'm no filter "expert." I'm not an aquarium "gearhead." My thoughts on this topic are based, like everything I write- on my personal experience and ideas, laced with a healthy dose of "opinions" and 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.
I have used all sorts of filter systems on my BWBS style systems over the years, but the ones that I tend to use will 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, btw...so 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 those freakin' "Lily Pipes"- yes, I know that YOU may not think they're ugly, but I"m no fan of them as they are now. Why? We can have that discussion some other time, okay?
b) Sumps add water volume to your tank
c) Sumps provide an area where you can keep filter media, biological media, botanicals, wood, etc. to influence water conditions in the display. 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.
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?
"All in one" tanks, like my Innovative Marine "Fusion Lagoon" system, offer a great "hybrid" of a sump and an external filter, making an affordable, simple, aesthetically clean, easy-to-maintain-and-operate system.
Now, I realize that not everyone wants the 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 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.
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.
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.
Oh, and sponge filters are great- and those Matten Filters- because they are primarily biological filters and are relatively easy to hide in displays...
Now, I have spent a fair amount of time 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! And of course, it goes without saying that you can utilize all of these filters with the botanicals present in the display. Like, duh.
The real "issue", if you want to call it that- with filtration vis a vis our BWBS-style tanks 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.), darkest "tint" imaginable.
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 all 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.
(Yes, I stole another pic from our good friend, George Farmer, of his latest tank which demonstrates this beautifully!)
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.
These things are are all something we will see more of in the future...trust me.
In the mean time, you can use materials like carbon, Poly Filter, 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 clear tank- if that's what you want.
And of course, we recommend mechanical filtration media, like "noodles", filter pads, floss, etc., and of course, biological media.
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.
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...
So, yeah- use what works for you, benefits your fishes, and creates the best outcomes. At its best, this is a summary of ideas and hopefully, a brief dossier on potential things to do in the future.
Stay engaged. Stay bold. Stay curious. Stay inquisitive. Stay innovative...
And Stay Wet.