That "stuff on the bottom..."- Good, bad...or just part of the game?

If you recall my little rant on Saturday, I was sort of singing the praises of the idea of an aquarium with a fairly large amount of organic material in it. Now, when you think about it, the botanical-style aquarium sort of falls into that category, huh? Leaves and botanicals certainly add to the "something" to an aquarium, don't they?

Sure, but is this a negative? 

If you look at a lot of the underwater photos and videos taken in the natural habitats of our fishes that, thankfully, are becoming more and more popular and abundant than ever, you see a lot of "stuff" in the water column, on the bottom, etc. Natural streams are not always the pristine-looking "nature aquarium" subjects of our dreams, are they?

Not really. Rather, many of the environments from which the fishes we love hail are anything but "pristine" assemblages of rock, wood, and plants. They have a lot of "stuff" in them, ranging from clumps of algae to seed pods, palm fronds, etc, up to submerged logs.

Now, in many of the photos and videos that I've poured over in recent years, the most common items you see on the bottom are...shocker- leaves! Yeah, they're almost every aquatic environment you see, ranging from ponds to slow moving jungle streams, to larger rivers. Sure, in swift-current scenarios, you're less likely to see large beds of leaves, but you still see them. 

Which is why, when I first started playing with leaves, that I was so astounded that more hobbyists haven't incorporated them into their displays. You'd see them in the tanks of a few biotope freaks, which were seen largely as "fringe-dwelling" novelties, and maybe some dedicated cichlid and betta breeders- but that was really the extent of it. Now, once I got our of my "reefkeeping" mindset of adding all sorts of stuff to a tank, I was able to look at it objectively. 

As we've discussed ad naseum here, I think one of the biggest initial reason was that the look was utterly "alien" to our aesthetic sensibilities. I mean, "Clutter" on the bottom? How is that "natural?"

And, perhaps even more important, the idea of throwing things like leaves and seed pods into a tank- a carefully managed artificial world, seemed like simply "polluting" what was long suggested should be as pristine a system as possible. And brown water= "dirty", right? Yeah. A lot of aquarists still equate tannin-stained water with "dirt." I know, I know- an aquarium is not an open, natural system, yet if well-managed, it can function beautifully for years and years, right?

So there were the two biggest factors. One was based on a prevailing mindset of what a tank should look like, and the other based on a perception of the possible environmental impact on a carefully constructed aquarium environment. Both were valid points. However, after years of experimenting with leaves, botanicals, and other natural materials in aquariums, and with a growing global community of hobbyists doing the same daily, the mental roadblocks to this different approach are starting to fall. We're seeing all sorts of tanks being created by all sorts of hobbyists, which in years past would garner far more hushed whispers and criticisms than gasps of envy.

So, with the above historic concerns in mind, what exactly is the impact of a bunch of stuff on the bottom in your tank? Well, on the most superficial of levels, the water turns brown. We know that. And, if your water has a lower general hardness, it shifts towards an acidic pH. Again, something we already know. So what are the other impacts? Well, for one thing, decomposing material of plant origin probably contains stuff like sugars, lignin, and all sorts of organic compounds. Some of these substances are utilized by various organisms, like bacteria and fungi, which work to break it down. Algae, and plants (if present) will utilize some of them as well, such as phosphates, nitrates, etc.

Now, the "organics" that we have used as a red flag to discourage throwing this stuff into tanks in years past can accumulate and even be problematic- if you don't have necessary control and export processes in place to deal with them. What would these processes be? Well, to start with- Decent water movement and filtration, to physically remove any debris. Use of some chemical filtration media, such as organic scavenger resins, which tend not to remove the "tint", but act upon specific compounds, like nitrate, phosphate, etc. And of course, water changes. Yeah, the centuries old, tried-and-true process of exchanging water is probably the single most important aspect of nutrient control and export for any system, traditional, botanical, etc. There is no substitute for diluting organic impurities through regularly-scheduled water changes, IMHO.

And those are only some of the most obvious aspects of nutrient control and export, really. It even gets down to stuff like not overstocking and overfeeding your tank. Carefully removing uneaten food. Nothing that is really out of the ordinary. I can tell you from experience in every botanical-style tank that I have set up since 2012, that I have never experienced more than barely detectible levels of nitrate (like, less than 5ppm, if at all) and phosphate (like 0.05ppm or less). This despite large amounts of leaves, seed pods, etc. being present. Sound, time-tested husbandry techniques will make managing a heavily-botanical-laden aquarium as easily manageable as any other aquarium system, in my experience. Certainly more forgiving than an "SPS" reef system, "high tech" planted tank, Mbuna tank, or brackish water system, in my experience!

When people see things like biofilms and possibly even a little algae forming on botanicals in an aquarium for the first time, the initial reaction for many would be to freak out and immediately submit to the "I told you so's" offered up by the "armchair experts" who've never ran a botanical-style tank. Before running off and tearing your tank apart- examine it. Look at the water chemistry. Look at the fishes. Take another look at some underwater pics and videos of natural habitats and realize that this is exactly what to expect in a system where these materials are present. And take comfort in knowing that, in an aquarium, these biofilms will typically subside once the aquarium establishes itself. A "mental shift", patience, and the passage of time are the "corrective measures" you need to employ here. Oh, and a desire to understand what's happening...

Now again, I'm speaking from my personal experience with many tanks set up in this fashion. I'm not a scientist, having completed a huge number of water quality experiments of every conceivable type on my tanks. And I'll tell you categorically that if you approach the management of a botanical-style blackwater aquarium in a nonchalant, irresponsible manner, you'll be in for a humbling experience. In my experience, there is nothing inherently more challenging or more dangerous about these types of tanks than there is with any other speciality system. I think that I do a pretty good job of managing the water quality in my aquariums. There's no magic here. Like many of you, I do the work necessary to keep my aquariums operating in a healthy state. In my opinion, NO aquarium is "set and forget", and you'll be in for a rude awakening with a blackwater, botanical-style tank- or any tank- if you take that approach.

And, with the scientifically-validated benefits to fish from humic substances present in blackwater, the "upside" to what was long popularly perceived as dirty tanks is becoming more and more obvious. And the aesthetics, dynamics, and interest created in your aquarium by "that stuff on the bottom" can become a fascinating, obsessive new passion for you within the aquarium hobby if you're not careful!

So, keep applying skill and common sense to your aquariums. Stay focused on husbandry. Stay engaged. Share what you've learned.

Stay excited. Stay fascinated.

And stay wet.


Scott Fellman

Tannin Aquatics





Scott Fellman
Scott Fellman


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