The application...

After quite a few years of doing this crazy botanical-style aquarium thing, I've begun to realize that one of the "constants" is that we all enjoy what we do in our own special way. And there are as many ways to utilize botanicals in the aquarium as there are aquairums!

One of the most common questions we receive from newcomers to the botanical-style aquarium world is, "How can I use botanicals to create blackwater without having them in the display tank?"

In other words, you like the "tinted look", but you're not the biofilms, decompositions, and other "nonsense" (as my wife calls it) which goes with using botanicals as part of the "aquascape." 

I mean, the idea of utilizing botanical materials to create blackwater-type conditions (tinted water, soft and acid) is as old as the idea of blackwater aquariums. Of course, the biggest misunderstanding is the assumption that that botanicals and leaves can soften water. 

They can't. We've gone over this many times.  We'll do it again here, one more time!

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? That shit's kind of uninspired! 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 time!) 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!  

It will also make it clear, once and for all, what botanicals cannot do in this context!

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 purchase- and totally with it!  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. Rad. 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 somewhat, 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, and water with little to no carbonate hardness.

And of course, the next inevitable question is, "How much leaves/botnaicals/etc. should I use to achieve "X" pH in my tank?"

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, and stupidly misleading at worst.

I know, it sounds like a cheap "cop out" from having to answer this, but the reality is that there simply IS no single answer or "formula" that we can use with any degree of dependability.

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?  What bot apicals have larger amounts of these substances in them than others? Etc., etc., etc.  

It's unpredictable at best, IMHO.

Blackwater "extracts" fall into the same category, as far as I am concerned.

Yes, these are generally quality products. And they will impart the aforementioned humic substances into the water.  Yet, how much, and for how long, I couldn't tell you. I'd suspect less than if you have an "on board" source of botnaicals releasing these materials continuously, but even that is speculative on my part. 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, "Just add this and you've gone Orinoco, baby!"

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

Now, sure, you can get the "look" and some aspects of the environment without having to use decomposing leaves and botanicals in your tank. A win for some people, I suppose! It's just a different approach...Not necessarily "better"- or "worse", either.

Just different.

Now, 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 as we proffer is admittedly imprecise, subject to many variables (as re-hashed above), and unpredictable for the most part.

Now, to be honest, I sort of like that aspect! 

Oh, and you already know how I feel about using the "tea" from preparation of botanicals as a "home-brewed" sort of "blackwater extract..."

If not, I'll touch on it again: 

One of the things that I have an issue with in our little hobby sector is the desire by many "tinters" to make use of the water in which the initial preparation of our botanicals takes place in as a form of "blackwater tea" or "blackwater extract."

Now, while on the surface, there is nothing inherently "wrong" with the idea, I think that in our case, we need to consider exactly why we boil/soak our botanicals before using them in the aquarium to begin with. 

I personally discard the "tea" that results from the initial preparation of botanicals- and I recommend that you do, too.

Here's why:

As I have mentioned many times before, the purpose of the initial "boil and soak" is to release some of the pollutants (dust, dirt, etc.) bound up in the outer tissues of the botanicals. It's also to "soften" the leaves/botanicals that you're using to help them absorb water and sink more easily. As a result, a lot of organic materials, such as lignin, proteins, and other stuff, in addition tannins and humic substances- are released.

So, why on earth would you want a concentrated "tea" of dirt, surface pollutants, and other organics in your aquarium as a home-brewed "blackwater extract?" And how much do you add? I mean, what is the "concentration" of desirable materials in the tea relative to the water? I mean, it's not an easy, quick, clean thing to figure, right?

There is so much we don't know. We're just learning how to utilize the botanicals themselves correctly and safely; why push it further by adding what amounts to a concentrated "waste extract" to our tanks?

You can do whatever you want. However, since you ask- that's my thinking on the subject! You won't hear me advising you to add this water to your tanks.

So, with a basic understanding of what these materials can and can't do, and a little warning on adding that much-ballyhooed "tea" to your tanks, what's the alternative to using leaves and pods and cones and such in your display tank?

Use 'em in the filter.

Toss some prepared botnaicals into a mesh filter bag in your canister filter, where they'll receive a continuous flow of water, and they will more rapidly impart their humic substances, tannins, and other compounds into the water.

Or, you can purchase a simple fluidized media reactor- same thing...And no "mess", either! It's self-contained and keeps any debris out of your tank- perfect or those who want the "color" and not the "aesthetics..."

No matter how you utilize botanicals, they WILL influence the chemistry of your aquarium water...somewhat.  And everyone talks about it; none of us know for sure HOW much and to what extent..

And of course, that's why there is so much speculation and misinformation and "stuff" propagated out there online. It's been that way for a long time! And still, 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.

For the one millionth time (and the second time in this piece!):

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. 

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. Just because you're using Alder Cones or other botanicals in a reactor instead of in the display doesn't mean that you're circumventing any need to monitor things, right?

It doesn't mean their chemical/ecological impact on your tank is really that different than if you have them sitting on the bottom of your substrate, right?

Well, chemical- likely no. Ecological- perhaps.

Having that material in the tank "proper", on/in the substrate- interacting with the overall biotia of your tank IS a difference, imho. The possibilities for other life forms to feed off, metabolize, colonize, and otherwise utilize the botanicals "physically" as well as biochemically IS different, right?

I think so. 

In my opinion, a botanical-style aquarium (blackwater or otherwise), depends on these materials being "on board" (ie; physically in the tank) to provide/perform these functions. Using "extracts", maintaining botanical materials in a reactor is a different sort of thing. Not quite a botanical-style aquarium. You get, say "70% of the benefits" or whatever by NOT placing the materials in the aquarium. 

And that difference is the difference between a botanical-style aquarium and an aquarium that utilizes botanical materials simply to influence the water chemistry or apply tinting "effects".

It's about the "application" of the botanicals.

It's about understanding what these materials are potentially capable of doing; two they impact the life forms in your aquarium. And even more important- how to manage these aquariums long term. That's the evolving "art and science" that we are all working on.

Stay intrigued. Stay studious. Stay excited. Stay diligent. Stay informed...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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