Bottoms Up...Again.

There are topics you bring up because they're relevant, interesting, and very integral to your aquatic "practice"- stuff like proper water conditions to induce spawning in specific fishes, system design for optimum environmental management and efficiency, or reviews of the dietary requirements of that fun killifish species. Important, highly pivotal topics which are, in a way "foundational."

Today's topic is not one of them. :)

Have you noticed that the vast majority of the botanical-style, blackwater aquariums that our community has created involve light-colored sand substrates, versus the darker, more earthy-looking ones that are available for planted tanks?

Told you this was groundbreaking (hey, it's Sunday morning at like's what's on my mind!)...

Seriously, though, I'm curious what types of substrates we use and why. Now, if you go to my favorite source of inspiration- Mother Nature- it's pretty obvious that the majority of blackwater stream substrates are a fine white sand, or a clay like material called "podzol", which comprises a lot of the geology in Amazonia and other parts of the South American biosphere. It influences the chemical composition of the water in a significant way. And, yeah, if we're trying to mimic many of the habitats of this region, a light-colored sand substrate is a great place to start, huh?


In previous blogs, we've touched on the idea of utilizing different botanical-derived materials, like leaves, coconut coir-based products, peat, bark, leaves, and botanicals as a "top-dressing" over a very thin layer of substrate, or a mix of materials comprising the entire substrate. I know a few of you who are really working this concept! This is, of course, one of the basic things we do in the botanical style aquarium. However, it's almost always over the whitish sand. 

So, I guess where I'm at (as a guy who's about to set up another new, strictly decorative blackwater tank!) is wether or not any of you have utilize darker substrates or those planted aquariums soils within the context of a blackwater, botanical style system, as opposed to a strictly planted tank? I agree that these substrates offer some interesting "functional" possibilities, even for non-planted tanks- such as influencing pH, etc. I'm curious how they would function when "inundated" with a mix of botanical materials.

With an almost complete lack of buffering capacity, I'm curious what kinds of low pH levels could be achieved by utilizing them, and how easy it would be to maintain significantly lower levels without having to "fight off" the inherent buffering capacity of many commercial sand-type substrates.

Obscure thoughts, but oh, how my active mind wanders in those rare periods of "down time", like in the car, on airplanes, or when trying to fall asleep (I can't tell you how many systems I've "built" under those circumstances! I think I even "bred" a Red version of the Black Ghost Knifefish in one of these "fantasy achievement" sessions! It was cool.)

Anyhow, I think these substrates could effectively mimic many natural habitats, particularly African and Asian ones, where peat and other darker materials, including those of volcanic origin may comprise much of the composition. I mean, one could do exclusively peat or "Cutch Bark" or "Substrate Fino"/"Fundo Tropical" substrates (after significant preparation), and this would have the basis of an interesting experiment!  Or like, mud...

However, I'm curious about your experience with darker-colored or planted tank-intended substrates as respects to our botanical aquarium "practices."

Feedback, please! 

As always, keep an open, active mind.

Stay innovative. Stay creative. Stay motivated. Stay experimental...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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