"Under the influence of botanicals"

Damn, that sounds like it should be illegal or "18 and up" or something, but I kind of figured the strange title would apply nicely to today's topic!

One of the questions we've been getting a lot of lately is about the ability of botanicals to influence the pH and hardness of the water. Despite our efforts here among our community to point out how much (or how little) botanicals can influence these environmental parameters, there is a lot of confusion among the general aquatic community.

The perception seems to be based on the appearance of the water (yeah, the "tint!"); that being that if water is brown or golden or whatever, it must be sot and acidic! Like the old expression that "You can't judge a book by its cover", you can't really gauge the environmental parameters of an aquarium by it's color, either. (Damn. We need to come up with something "catchier", huh? LOL)

First off, without delving too far into basic water chemistry, which I have neither the desire or ability to explain in simple terms, I think everyone needs to kind of delve into google and refresh (or educate for the first tiem!) themselves on the concepts of carbonate hardness and pH. This will set you up well for understanding exactly what these parameters mean, and how they can impact your fishes.

Suffice it too say, botanicals cannot influence the carbonate hardness of the water! They cannot "soften" it. Soft water is water that contains low concentrations of ions- particularly calcium and magnesium. In order to achieve "soft water", these ions need to be removed from the water. 

In nature, soft water occurs where rainfall accumulates and rivers and streams are formed over hard, impervious, calcium-poor rocks. Geology, as we've discussed before, is a HUGE influencer of the carbonate hardness of the water in wild ecosystems (and in aquariums, for that matter!). For our purposes, the process of "ion exchange" is the most efficient way to soften water for aquarium use. And that is easily achieved by utilizing an RO/DI ("reverse osmosis/deionization) unit, of which dozens are available for hobbyist use!

For a detailed explanation of THAT process, just google it! My head spins just thinking of how to explain it in a non-confusing matter. In my opinion, an RO/DI unit is one of the fundamental investments that any serious aquarist should make. Yeah, they're a couple hundred U.S. dollars to sort, and arguments could be made about their efficiency, etc., but if you really want to create optimum conditions for fishes requiring soft, acidic water, for most of us it's the best way to go. 

For those of you who have naturally soft water where you live, Mazel Tov. Awesome. However, for the rest of us, we need to buy a damn RO/DI unit and be done with it. 🤓

Now, botanicals DO have the ability to influence the pH of the water, particularly when you are using RO/DI water with little to no carbonate hardness. Because tannins and humic/other acids are released by many botanical materials when immersed in water, the impact can be rather significant if you have enough botanical material in an aquarium of a given size.

Major spoiler: No matter what anyone says- product manufacturer, botanical vendor, "expert aquarist"- anyone- there is simply no "one size fits all" sort of "recipe" that tells you that "X amount of Catappa leaves will drop the pH of a liter of water by 'X' points. There are just so many variables as to make such assertions well- a guess at best, stupidly misleading at worst.

I mean, what is the starting pH of the water? What kind of substrate do you have? What's the temp? Are you utilizing chemical filtration media? How many grams of what specific tannins acid or humic acid are contained in that particular batch of leaves or botanicals? How much makes it into the water column, and after how long?  Etc., etc., etc.  

Blackwater "extracts fall into the same category, as far as I am concerned. Yes, they will impart the aforementioned humic substances into the water. They can influence the pH, will do nothing to the hardness, and make the water a pretty brown color. But that's it, IMHO. No "magic bullet." No "add this and you've gone Orinoco!"

Nope. Like everything else, if it sounds too cool to be true, it usually is. 

You could utilize acid solutions to drop the pH reliably and with precision verifiable by testing. That's a little more serious proposition, but entirely doable. And it is something many hobbyists have done. You can do some research online and find out about this. However, trying to do it the "natural" way is imprecise, subject to many variables (as re-hased above), and unpredictable for the most part.

I sort of like that aspect.

Botanical-style aquariums are not "plug-and-play", "set-and-forget" systems. They are individual, unique, and highly dynamic closed microcosms which require continuous observation and maintenance- like any aquarium. 

Yet, for all of these caveats, I've found blackwater, botanical-style aquariums to be some of the most stable, dynamic, and easy to maintain aquariums I've ever kept, one you get them dialed in. 

Yet, in todays internet-fuled hobby, the misconceptions- good and bad- continue.

So, let's get that thinking out of our heads once and for all. Yes, you can use botanicals to influence the pH of your water if the carbonate hardness is minimal. They can and will impart humic substances and tannins into the water. They will color the water. How much and to what extent is something that is simply unpredictable. 

This is no different than the practice of peat filtration to lower pH of water, which has been preferred by hobbyists for decades. There never was any definite study or  lab testing done to know just how much peat per gallon would influence the pH by "x"...again, this idea of utilizing natural materials to influence the aquarium environment, although not new, has always been as much of an "art" as it is a "science." 

You will perhaps develop over time a technique to get your water conditions "roughly" where you want them, but that takes trial and error, replication of process, and lots of patience! Utilizing botanicals for water chemistry manipulation is NOT an exact science at this point. Sure, we can monitor pH and alkalinity, even test for the presence of tannins. However, what does it mean if there are "x" ppm of "tannins" in your water? There are three main classes of tannins, but literally hundreds of types.

Okay, before you get all depressed and think this is all for not, there's good news. The work we've done with botanical materials in our aquariums has yielded a different type of "measurable" result: Noticeable increase in color, vitality, overall health, and yes- spawning behavior and egg viability in species which come from soft, acidic blackwater conditions in nature.

We have to remind ourselves that, even with our best efforts, and considerable water testing, that at best, any aquarium is merely a facsimile of a natural ecosystem. If you're utilizing botanicals in your aquariums, you're doing "something." And that "something" is generally recreating some of the environmental parameters found in the natural habitats of our fishes. we just may not be able to measure exactly what that "something" is.

Shit. Right? 

Not perfect. Not even close. But way better than throwing our wild-collected Cardinal Tetras into our Los Angeles tapwater, right?


For the first couple of years (okay, and continuing its today) of our existence here at Tannin, the biggest concern I have had is encouraging aquarists to utilize botanicals carefully, and to understand that in addition to the aforementioned potential pH impact, they can and will add bio-load to the water, requiring sufficient nutrient export mechanisms (ie; biological filtration, use of chemical filtration media, and manual husbandry practices, like water exchanges) to handle the materials being added into your closed ecosystem.

Adding too many botanicals too quickly is a bad idea, as we've discussed numerous times in this blog. There is absolutely no reason to rush and dump the entire contents of your "Geo Pack" into your 40-gallon aquarium at once and not expect potentially bad outcomes. What happens to your biological filtration when you add 200 fishes to your 40-gallon tank at one time? Bad shit, that's what happens. It gets overwhelmed as the bacteria struggle to catch up and break down the ensuing organic wastes. And as a  result, oxygen levels plummet, CO2 rises, nitrite and ammonia can increase...Big problems can ensue.

However, you know this already. It's "Aquarium Keeping 101."

So, I implore you as always to deploy patience, time, observation, and common sense when adding botanicals to any aquarium, particularly a  long-established one. This is not a "new thing" or some sudden warning we're releasing. We've been proffering this advice since day one of our operation, and will continue to push this practice of being careful forever.

It's just the common sense, responsible way to go!

Okay, now that I've probably shattered some perceptions for some, and maybe scared the living shit out of a few others, I want to encourage you to experiment responsibly with botanicals, as you have been doing for the three years we've been around- and as aquarists have for the better part of a century before.

Although sometimes frustratingly imprecise and as much of an "art" as it is a science, the "New Botanical" movement- yeah, I'm calling it a "movement"- is ripe for experimentation, innovation, and breakthrough. It's already yielded some amazing results for many, and the future is really exciting! Everyone is more -or-less on equal footing here, with the capacity to contribute to the state of the art to what has always been an exciting, yet misunderstood  frontier in the aquarium hobby. 

Aquariums "under the influence" of botanicals are fascinating, aesthetically pleasing, and biologically promising systems that will continue to yield interesting results for decades to come. Now is the time to experiment. To strive. To observe. To test. To progress.

Stay excited. Stay fascinated. Stay skeptical. Stay careful. Stay bold...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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