One of the more exciting times in the life cycle of a botanical-style aquarium is a couple of weeks after the initial setup. It's that fascinating time when the nitrogen cycle is established, the tank is "running in", and the botanicals and leaves lose that crisp, "brand-spankin' new" look and start to acquire a "patina" of biocover, or simply begin to "soften up" a bit.

The early weeks and months in the aquarium's life cycle really "set the tone", in my opinion, for how the tank is likely to function over time. It's a magical time when your tank begins it's progression from just a concept to a living, breathing microcosm. The biological processes are kicking in, and the business of life- the establishment of micororganisms, biofilms, and yeah- even algal growth- is increasingly evident. 

I am a big believer in stability, and deploying patience, using time-honored nutrient control/export techniques, and applying a healthy dose of observation and common sense all contribute to the ultimate stability and success of our blackwater/botanical-style aquariums just as they would to any other type of system.

One of the things that we all experience with these types of systems is an initial burst of tint-producing tannins, which likely will provide a significant amount of "visible tint" to the water. If you're not using activated carbon or some other filtration media, tis tint will be more pronounced and likely last longer than if you're actively removing it with these materials!

You might also experience a bit of initial cloudiness...this could either be physical dust or other materials released from the tissues botanicals, or even a burst of bacteria/microorganisms. Not really sure, but it usually passes quickly with minimal, if any intervention on your part. Oh, and not everyone experiences this...often this is a phenomenon which seems to happen in brand new tanks...so it might not even be directly attributable to the presence of the botanicals (well, at least not 100%). Could be the sand, or other dust/dirt from the other hardscape materials or the tank itself.

While we're on the subject of the nitrogen cycling of new tanks, one of the things I've noticed about my botanical-style/blackwater aquariums is that they "cycle" very quickly. Like, often in less than a week. I think it's got something to do with a large influx of botanical materials in a new system. The same factors that would endanger an established system might simply contribute to a rapid growth of bacteria.

Interestingly, over the years, I've also found that nitrate accumulation tends to be almost nonexistent in my botanical-style aquairums. Now, I don't know if that's something which you've noticed, too? I simply have never seen a nitrate accumulation more than 0.2mg/L!

Despite what I hypothesized would happen in my early years of playing with this style of aquarium, when I really got into blackwater, botanical-style aquariums, I found that they always produce little to no detectible nitrate, despite utilizing a lot of botanical material within the tank that was breaking down. I would have thought, at least on the surface, that there would be some detectible nitrate. Now, this is interesting, but I'm not the only one who has reported this. Many of you have.

My hypothesis is that, yes, the material is breaking down, and contributing to the biological "load" of the system- but with an abundance of microorganisms living in, on, and among the botanical materials in the aquarium, and with regular frequent water changes, there is a very efficient processing of nutrients occurring. This is purely speculation on my part, but I think it's as good a guess as any, based on the repeated similar results I've achieved in every single blackwater/botanical-style aquarium I've kept for the last 7 or 8 years!

I'm sure that a more sophisticated explanation, revolving around the presence of "on- board carbon sources" and other biological processes is the reason. I think that we're sort of looking at a freshwater equivalent of a reef aquarium in many respects, where, instead of "live rock", a lot of the microbial population and biological processes occur within and upon the surfaces of the botanicals themselves.

Almost like "biopellets" in a reef tank, perhaps the botanicals are not only a carbon source for beneficial bacteria- they're also a sort of biological filtration "substrate" for them to colonize on. Again, speculative, and needing some more rigorous scientific investigation to verify one way or another, but it's been my "working hypothesis" for several years.

In my opinion, once they get through the initial startup phase, blackwater/botanical-style systems seem to run incredibly smoothly and in a very stable manner. If you adhere to a regular, yet simple maintenance schedule, obey the long-established common-sense "rules" of aquarium husbandry, and don't go crazy with radical overstocking or trying to speed up things too much by dumping tons of botanicals into your tank in a brief span of time, these systems run almost predictably, IMHO.

And speaking of "maintenance"-  I'll concede that one of the "bummers" of botanical-style aquarium keeping is that you will likely have to clean/replace prefilters, micron socks, and filter pads more frequently. Just like in nature, as the botanicals (leaves, in particular) begin to break down, you'll see some of the material suspended in the water column from time to time, and the bits and pieces which get pulled into your filter will definitely slow down the flow over time. The best solution, IMHO, is to simply change prefilters frequently and clean pumps/powerheads regularly as part of your weekly maintenance regimen.

Remember, you're dealing with a tank filled with decomposing botanical materials. Good overall husbandry is necessary to keep your tank stable and healthy- and that includes the dreaded (by many, that is) regular water exchanges. At the very least, you'll likely be cleaning and/or replacing pre filter media as part of your routine, and that's typically a weekly-to bi-weekly thing.

And, during my water exchanges, I'm merely siphoning water from down low in the water column. I'm a sort of "leave 'em alone as they decompose" kind of guy. And I'm not going to go into all the nuances of water preparation, etc. You have your ways and they work for you. It's not really rocket science or anything, but everyone has their own techniques. The one "constant" is to perform regular water exchanges in your botanical-style aquariums.

Just sort of goes with the territory here.

And what about water testing?

Personally, I think it's a really good idea. For many hobbyists, water testing is a periodic thing, done on an "as I feel it" basis. Personally, I think the benefits of a more regular testing schedule yields a lot of good benefits for us.

Your testing regimen should include things like pH, TDS, alkalinity, and if you're so inclined, nitrate and phosphate. Logging this information over time will give us all some good data upon which to develop our expectations and "best practices" for water quality management. It's important for the hobby overall to document as much information as possible about how our botanical-style/blackwater aquariums establish and operate. This gives the widest variety of hobbyists the most reasonable set of expectations about these systems.

Remember, it isn't just about a new aesthetic approach.

It's about understanding and processing what's happening in the little aquatic ecosystem you've created. It's about asking questions, modifying technique, and playing hunches- all skills that we as hobbyists have practiced for generations. When you distill it all- we're still "just keeping an aquarium;" yet one that I feel is a far more natural, dynamic, and potentially game-changing style for the hobby.

One that we need no longer be afraid of.

It's about understanding what to expect, how our systems evolve, and how we manage them.

And most important- how we enjoy them.

Managing a botanical aquarium offers opportunities, challenges, and educational experiences that we can use to push the "state of the art" of botanical, blackwater aquariums- and to add to the growing body of aquarium knowledge about managing these unique systems over the long term.

And sharing your experiences- good and bad- will provide those who follow with more confidence to follow in your footsteps, creating their own aquariums, pushing the limits in their own way- and growing the global "tint community"- and aquarium hobby in general- through their efforts.

Stay diligent. Stay methodical. Stay curious. Stay helpful. Stay collaborative. Stay open-minded...And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

January 10, 2019

Great information, Johnny! This is actually pretty interesting to me, as the implications for biological stability and the dynamic of planted blackwater/botanical-style aquairiums…I think we need to have more discussions on this stuff! and more articles (hint, hint… 😆)

Jonny Archer
Jonny Archer

January 09, 2019

Thought I would just weigh in on your Nitrate theory.

Yes the botanicals act like the bio pellets for marines. Because they are mainly lignin which consists of Carbon, Hydrogen and Oxygen makes them perfect for Nitrate fixation Which is brilliant for fish only systems!

On a side note, I wonder if there’s a correlation between Nitrate sensitive fish and black water in the wild?

The breakdown of the botanicals will strip a tank of Nitrogen Potassium and phosphate (NPK). So a word of caution to my fellow scapers. Because of this effect, the water can become depleted of N,P,K and therefore stunt your plant growth. I found in my scape I had to almost double the dosage of my NPK fertilisers to compensate for this effect. If your after a more natural way to introduce NPK you can feed the fish more food, however, caution is needed as more food can cause a myriad of other problems.

Oh, another thing I notice when I added more NPK and more fish food into my aquascape I felt that my botanical decomposed faster which would confirm your theory. Having said that it was an observation so I would take the faster decomposition with a pinch of salt as its very anecdotal.

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