Keeping it real...

We're some four years into our existence here at Tannin Aquatics, and it's been amazing to see botanical-style aquariums starting to really catch on and become a definitive "movement" within the hobby. 

It seems that everywhere we turn, there is a growing interest in adding "twigs and nuts" to our aquariums, with more and more aquarists considering (and actually creating!) a botanical-style, blackwater aquarium. This idea, formerly a sort of "side show" novelty, is rapidly moving into the mainstream of aquarium technique, and lots of interesting developments are happening.

This is quite gratifying to me, as it's something I loved for a long time, with seemingly very few friends to share it with. In this instance, "scratching my own itch" to start Tannin certainly seems like it was a good idea! Now, the word "botanicals" is something we see quite a bit in the hobby. I'd be hard-pressed to have seen the term even used in the aquarium context prior to our debut in 2015. I've been told by some people that botanicals in aquariums are sort of a "trend."

Of course, whenever you see something becoming an emerging "trend" (Urghhh.. I HATE that word when used in the context of an aquarium topic!), you will see hobbyists making incorrect assumptions, having general misconceptions, and occasionally, unintentionally spreading wrong information about stuff. You know, regurgitating outdated or erroneous information that's been floating around out there on line for decades...

It's often a function of the fact that some of this stuff has been either under-utilized, completely misunderstood, or simply not appreciated for so long, that we've simply not really considered the dynamics involved in this context. 

Totally understandable, really.

And of course, being one of the leading proponents (and arguably, one of the more visible and one of the freaking LOUDEST) of this type of aquarium keeping, we have an obligation to the hobby community to provide correct information and clarification whenever possible, and to advise when we think something that's bandied about might be incorrect. And, when assumptions are becoming "fact" in our discussions, we do need to address them in our discussions from time to time.

Of course, one of the best ways to "keep it real" and address this kind of stuff is tell it like it is!

And it all starts with getting one thing straight right from the start...

As we have said like 140,000 times already, no one "invented" the idea of using botanicals in aquariums- least of all, us. However, we have made it our mission to educate, elevate and innovate in this world, so let's get to it!

Here are a few topics that we've seen discussed from time to time which, in my opinion, need to be clarified and thought through a bit before making conclusions. Obviously there are like 10,000 other more topics out there, and we could probably write a column on each one of these! (and we just might over time, right?)

So, here's a start; the beginning of a dialogue which might provide some clarity on some important aspects of the blackwater, botanical-style aquarium:

1) Botanicals cannot soften hard water. This is one of the more persistent misconceptions floating around. It started decades ago, with hobbyists thinking that leaves could do it, and it's continued right up until the present. Now, it's been proferred by some that materials such as peat moss can act to some extent as  a sort of "ion exchange resin", removing some minerals from the water and replacing them with humic acids, and perhaps this is where the idea that "all botanicals" can influence water chemistry accordingly arises. Botanical items (leaves, wood, seed pods, cones, etc.) do contain tannins and humic substances, and if used in sufficient quantities, can certainly lower the pH somewhat in water which is low in carbonate hardness.

However, these botanicals themselves simply cannot lower the hardness of your water. That needs to be accomplished by a process of ion exchange (such as reverse osmosis/deionization). If you start with hard, alkaline source water (which contains lots of dissolved minerals), and toss in some leaves or seed pods, or whatever, the botanicals will essentially do nothing to remove them.

"Soft" water is water that contains low levels of dissolved minerals, and as such, has lower ability to absorb acid substances, which will accumulate and lower the pH. That's why the effectiveness of botanicals in lowering pH can be significant in soft water. We've addressed this before, and you can find lots of articles on water chemistry on line.


2) Don't let the tint fool you. Remember, the visual color change imparted to the water via the aforementioned tannins is not an indication that you have soft, acidic water. In the absence of chemical filtration media such as activated carbon, which remove coloring agents from the water, the tint will be most evident as these materials enter the water.

However, don't forget that you can still have very hard, alkaline water and have some color. Just look at your municipality's annual water report...they actually mention visual tint" in their assays. So I guess one could call tint a "vanity metric" (to steal a marketing term) in our world, that it's really an observation of "cosmetic appearance" versus a manifestation of functionality (ie; lower pH and hardness).


3) There is no "recipe" for how many botanical materials will accomplish a given affect within your aquarium water. Yeah, we've mentioned this dozens of times, and it warrants repeating. Although I can make crude estimates based on personal experiences with regard to how many leaves (for example) it took to lower my pH from ___ to ___ in water with little to no general hardness, it's both unrealistic and misleading for me or anyone to suggest that adding specific numbers of various botanicals to your tank can give you a specific effect.

If for no other reason than the fact there are countless variables in everyone's aquarium and water, and that the botanicals themselves, being natural materials, may have varying levels of pH-affecting tannins and such in a given sized leaf (as one example), we just can't quantify this. We might tell you to start with "x" number, just because I do- but it's not a "recipe", okay? You need to start off with what seems to be a reasonable number of materials and test your water regularly to determine the impact on your aquarium. It's still about nuance, exploration, and experimentation.

All changes need to be done slowly and carefully.


4) The creation of food webs is interesting, but is not spontaneous or even a "given" when utilizing botanical materials in your tank. Sure, we spend a lot of time talking about the concept of creating a system which facilitates the growth of significant quantities of organisms (such as microorganisms, fungi, small crustaceans, worms, and aquatic insects), but the reality is that just throwing  leaves and seed pods into your aquarium isn't the whole story.

Sure, as they decompose, they'll fuel some microbial growth, and generate biofilms and fungi. However, you'd likely need to "inoculate" your system with small crustaceans like Daphnia, Cyclops, Gammarus, etc. in order to have more complex and diverse food sources available to your fishes. And you'd need to do this prior to adding fishes (which will consume them rapidly!), or in the confines of a separate "refugium" installed solely for the purpose of cultivating these life forms. It's an interesting, and potentially game changing idea- particularly for fry rearing systems...

5) Botanicals will not give your aquarium a permanent, stable hardscape! Nope, by their very nature, these materials begin to break down as soon as they hit the water, so the "clock is ticking" as they say! Now, some materials (the more durable seed pods, etc.) will last longer than say, leaves, which break down in a matter of weeks. However, the vast majority of botanicals all begin to decompose and physically change appearance over time. And this is a cool thing, really...this is exactly what happens in nature. These materials create what could best be referred to as an "ephemeral" hardscape. One which might well be anchored by permanent pieces like rocks and driftwood, but is accented by the changing condition of the botanicals.

We like to refer to this as an "evolving" aquascape, and I think that's a pretty accurate descriptor. And it reflects both the charm and attraction of the blackwater, botanical-style aquarium. Unlike many "traditional" aquascaping approaches, a significant part of the appearance of the tank is driven almost solely by nature, and as such, will change as materials break down, are moved about, and/or covered with biofilms and algae.

This is exactly what happens in the wild, and is why we say that operating this type of aquarium requires a distinct "mental shift!" Now, you can of course, keep your aquascape looking pretty close to the way it started out if you regularly remove, clean, or replace the botanicals. However, this level of "intervention" may not appeal to everyone!


6) Botanical-style aquariums are not "set and forget" systems.  I mean, no aquarium really is. However, in the case of a botanical-style aquarium, it's pretty much a non-starter! Look, you're talking about a tank with (typically) soft, acidic water, a fish population, and a large quantity of materials which are breaking down steadily. This number of critical variables requires regular observation and management on the part of you, the aquarist.

I would not state categorically that these aquariums are teetering on the brink of disaster at all times. I personally have never had a "crash", or have seen rapidly rising, out-of-control nitrate levels in an actively managed blackwater, botanical-style aquarium. Like any type of aquarium, you need to observe, monitor, maintain, and track your aquarium's status as it evolves. You'll learn to spot emerging "trends" which may or may not prove problematic to your specific system. Sure, you don't need to apply the same high level of diligence that you might with say, a coral propagation system or Discus breeding tank, but the simple reality here is that you're going to have to get your hands wet.

7) Patience and the passage of time are the key ingredients. Over time, botanical-style tanks seem to reach a sort of "equilibrium", where you won't see significant parameter swings or changes. The bacterial population adjusts to the amount of materials in the tank, provided you don't continuously add large amounts stuff, overfeed, add large quantities of fishes, or make sudden, abrupt changes in procedure. Consistent practices always work best. 

These tanks are no more inherently unstable or "dangerous" (something we've heard in the past about blackwater/botanical-style tanks) than any other system. You just need to understand the dynamic, including things like biofilms, decomposition, and detritus, which might have scared the shit out of you in the past- as part of the "normal" for these aquariums. You simply need to embrace and accept the limitations of a given tank, and to not expect to simply "sit back, relax, and enjoy the flight" as they say. Don't expect sudden shifts for the better or the worst.

Stay consistent, involved, observant, and above all- patient- and you'll be just fine. 


Sure, I could probably go on and on and cover all sorts of different, rather arcane topics and "myths" within this context, but I think we've addressed the most important- and common ones- that we see discussed. And hopefully, this provides a contextual framework for you to explore and discuss more about the design, construction, and management of botanical-style blackwater aquariums. 

It's an exciting, evolving area of the hobby, breaking out of the shadows of misconception and obscurity. We need to get better and better at sharing actual experiences with this stuff, rather than simply "regurgitating" second-hand information, as is so common in the hobby these days. And, like everything else, this type of evolution takes time. It takes patience. It takes understanding...and lots of sharing of firsthand information.

Are you up for it?

Stay engaged. Stay involved. Stay methodical. Stay excited. Stay curious...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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