How many of those? Understanding the dynamics of botanical aquariums...

Apart from, "What's the best botanical for________?",  the most common question we receive is "How many" can I use in a ___gallon/liter aquarium?"

The "how many" question is one that is really difficult to answer in a concrete manner. Why? Well, for one thing, there are a lot of variables involved in determining this, and no real solid "right or wrong" answer, in my opinion. I think there is a certain "instinctive feeling" that we have to go on here.

Botanicals, like anything we add into our aquariums, will influence the environment in which they are submerged. As natural materials, in addition to the much-discussed tannins and humic substances, they contain organics and other materials (lignin, etc.) in their tissues, which are broken down slightly when prepared through boiling, and may continue to be released over time into the water, contributing to both the "richness" of the environment and to the "biological load", or "bioload" of the aquarium.

As we all know, materials such as leaves and many of the "softer" botanicals will break down more quickly, imparting these materials into the aquatic environment. This is a "double-edged sword", because on one hand, your aquarium is receiving a nice dose of tannins and humic substances, while simultaneously receiving an increase in your bioload. And we know that all organisms and many materials present in the aquarium produce waste in one form or another (fishes and invertebrates in the form of solid or liquid excretions, and things like botanicals in the form of the organics they release from their tissues over time into the water column). These waste materials consume oxygen as micro-organisms consume them and break them down into their constituent nitrogen components, like ammonia, nitrite, and nitrate.

Without sounding too scary, or venturing into a deeply scientific discussion for which I am simply not qualified, suffice it to say that, for our purposes, you simply need to be aware that everything you add into your aquarium that may be broken down by microorganisms should be thought of as contributing to the bioload of the aquarium!

How do we address this or compensate for the "load" in our tanks? Through simple, time-tested methods of nutrient control and export, which have been detailed in countless books, articles, and forums in the fish world for decades. In summary, nutrient control and export techniques include things like regular water exchanges, use of chemical filtration, physical removal of decomposing materials, disciplined animal stocking, water movement, etc., etc., etc.

And the one "nutrient control and export" method not mentioned here is to employ good old common sense, judgment, and even intuition on your part. There is simply no substitute for your good judgement. If you see that your water is cloudy, your fishes are listless, and the aquarium smells, you probably don't even need to break out the test kits to know that something is wrong. Of course, testing is always the best way to confirm exactly what's going on in the water, but the reality is that your first line of defense is always observation.

In the context of botanicals, you simply need to use...your judgement. We have, for years, used considerable restraint when adding these materials to our own aquariums (particularly established ones!), choosing to go slow and gauge for ourselves the impact of our additions. And, since we launched Tannin Aquatics last year, we've been filling your brains with countless admonitions to go slowly, observe, test, and gauge for ourselves how much is "enough" for our aquariums.

We've discussed the "ugly" biofilms and occasional algae growth that are normal in systems continuing heavy loads of botanical materials. This has been part of that "mental leap" that we talk about so much- understanding what is "normal" in the context of a botanical-influenced aquarium and learning to embrace it rather than detest or fear it, as it is an expected, natural development within our aquariums. Understanding that this is simply what occurs in natural rivers and streams as well.

With all of the countless variables in every aquarium in the world, it's damn near impossible -and actually irresponsible- for us to recommend "x" number of whatever botanical per gallon/liter. Sure, there are some time-honored practices in terms of how many Catappa leaves or cones, for example, it takes to get a good tint in aquariums of roughly "x" many gallons/liters, but the reality is that each situation is completely different, and numerous factors contribute to the actual impact these additions will have in your specific system.

The recent piece by Vince Dollar here in "The Tint" addressed the benfits of humic substances and the potential impact of adding botanicals to our systems, in terms of pH and alkalinity. These are probably some of the most important items that you need to be aware of when venturing into the world of botanical-influenced aquariums. It's so much more than just getting a nice brown tint to your water, and it's important to understand that blackwater, botanical-influenced aquariums are different from conventional "white water" tanks in more ways than simple aesthetic ones.

We've said it before and we'll say it again: Blackwater, botanical-influenced "natural" aquariums are no more difficult to create and maintain than any other type of aquarium system. In terms of management, they are on par with say, an African Cichlid aquarium, but certainly not quite as much of a "dance" as a reef aquarium or high-tech planted, in terms of management. The big difference between a botanical-style system and a more "conventional" freshwater aquarium is that you simply need to have a greater awareness of the impacts of what you're doing on a regular basis, and need to understand, embrace, and nurture the natural processes that occur. Really, you don't need to have a chemistry or biology degree- you simply need to have an awareness of what is going on, because these aquariums embrace nature just a bit differently than what we're used to.

Oh, and they look different. :)

Hobbyists have been dabbling with blackwater, botanical-influenced aquariums for a long time. Tannin Aquatics did NOT "invent" this idea by any means. If you call us "thought leaders" in this area, as some have, we'll take that. Yet I reiterate again that the idea has been around for a while, but maybe we simply haven't put the pieces together. However, I think it's only quite recently that we as a hobby have started to move them out of the "oddity/sideshow" arena and into the more "mainstream" of the hobby as a viable, interesting choice on how to run an aquarium.

We're seeing a lot less of the "you can't run an aquarium like that" negative thinking (particularly from those cowboys on the forums who have never attempted keeping one in this fashion) in the hobby world than ever before. Maybe, maybe- we've helped "demystify" them  a bit and make the idea more appealing to some hobbyists, which is gratifying and exciting! We receive emails and messages nearly every day from hobbyists who have embarked on this journey and have fallen in love with the hobby all over again. Lots of "eureka!" moments, which is really awesome to see!

We're all still learning a lot of things about developing and managing these systems on almost a daily basis, as more and more hobbyists worldwide try them. They are not "the best" system for every fish or plant, obviously, and simply not attractive to every hobbyist. Not everyone wants brown water, piles of leaves, decomposing seed pods, and biofilms in their tanks. However, for those of us who enjoy the challenge, fascination, learning process, and of course, the aesthetics- these aquariums present a "ground-floor" opportunity to learn, experience, and share a growing body of knowledge about another unique natural approach to aquarium keeping.

We're happy to have you aboard with us on this adventure that we're all taking in together.

Stay excited. Stay adventurous. Stay creative. 

And Stay Wet.

Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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