Long term botanical-style aquarium practice- opening up the discussion...

One of the questions that were starting to see more of as we evolve in the blackwater, botanical aquarium specialty is, "What are the long-term implications for maintaining such tanks?" (okay, it's not always worded that succinctly, lol). Hobbyists are interested in how these systems function in the long term, specifically in regards to nutrient control and export processes...

Now, this is an area of great interest to me, as well. Over the many years that I've been expert,ending with and managing blackwater, botanical-style tanks, I've placed a lot of emphasis on water quality and environmental consistency. Now, on first glance, the impression you'd get from our practice is that these are "dirty", organic-heavy systems, with high levels of nitrates, phosphates, and dissolved organic compounds...Systems "teetering on the edge", if you will. 

And I suppose that's partially because of the very appearance of these tanks- filled with decomposing leaves, seed pods, accumulating biofilms, embracing detritus, etc. Oh, and that dark brown, tannin-stained water. On the surface, the uninitiated could easily conclude that you're playing with all of the ingredients for a potential disaster.

And then the reality sets in...

Most of us who have played with these types of aquariums have seen the exact opposite: Minimal, if any- detectible nitrates, phosphate, and remarkably stable pH values. The reality is that, one the tank is "set"- that is, once you're done with the initial adding of lots of botanicals, and wood, and leaves and such...Like any tank, these tanks seem to "find" some sort of equilibrium. I've said it many times and I think that it needs repeating: In my opinion, blackwater, botanical-style aquariums are no more difficult or "dangerous" to maintain than any other type of aquarium we work with. They simply have different "operating parameters", which, one you learn, create stable, long-term viable systems.

We've talked a lot about the pH and the concerns of ph "crashes"- which I personally, in over 23 years of playing with this type of tank- have never seen. I just haven't. I know that's a big issue for a lot of people- and I won't downplay it or dismiss it. However, the reality is that I personally- nor none of my close friends who play with these kinds of systems- have ever experienced this. 

Are we lucky?


Do we practice overall good aquarium husbandry?


That means we do water exchanges. Like, 10% or more weekly. Every freaking week. With the same kind of water (RO/DI, usually). We clean filter socks, pads, or any other media that we use. We don't feed recklessly. We don't overstock. We monitor basic water parameters weekly. We properly prepare and replace botanicals gradually and regularly.

Put is in for medals, right?

I mean, just because we do it with relatives ease and success doesn't mean that this is a piece of cake or anything. I get that. My point was not to "humble brag" or anything. Rather, it was to remind you that if a guy like me can be successful with this stuff, hobbyists with serious skill like you can RELALY be successful!

However, it should give you some comfort knowing that, in addition to myself an a few friends, hobbyists worldwide are playing with botanical-laden systems without anomalous crashes and disasters. Can bad stuff happen? Sure. The most common "disasters" we've seen have been by adding too many botanicals too quickly, resulting in excessive bacterial respiration- which, in turn, likely lowered the water's dissolved oxygen and increased CO2 levels rapidly to a dangerous rate. These effects happen at the same time and can lead to fishes gasping for oxygen at the surface- or worse.

But that's the extent of the "bad" that I've seen.  The idea of a pH "crash" is possible, I am sure...but I think it's largely avoidable, much like the CO2 increase. A pH "crash" is when the pH suddenly (and unintentionally) drops because of the release of acid into water with little or no buffering capacity...this can be dramatic and quick...But I think, once again, it would be caused because of our own actions- intentional or otherwise...Not something that is inherently "on standby" in a blackwater, botanical-style aquarium. Sure, we work with materials that can affect the pH..but it's not a ticking time bomb, if you add materials logically and slowly. Observation and patience are keys. 

Now, I am not a chemist, and I'll be the first to admit that what I'm using to justify my position is largely anecdotal, based on my operating many such systems over the years. I have not done rigorous controlled experiments on this stuff.  That being said, I'd welcome those with the interest and knowledge to conduct some cool experiments to see what we can learn! I am really of the opinion that WE as hobbyists are the causative factor of many of these "anomalous" events in our aquariums. They can almost always be traced back to some action which triggered the event...

If your continuously adding materials which drive down the pH in your tank, and it has insufficient buffering capacity- the pH will drop. How rapidly? Well, I couldn't' tell you. But I believe such "crashes" are quick, immediate responses to some causative factors. And I think they can be remedied equally as quickly. There is a lot of this stuff on hobby forums about working with pH, and quite frankly, I find it a bit too complex and tedious to understand and explain, so I recommend doing a "deep dive" on this stuff if it is a concern. It's out there! 

The potion of this extremely brief piece today is NOT to get into every aspect of water chemistry, management of botanical aquariums, and pH issues. Rather, it's to sort of open up a discussion on long-term management of botanical-style aquariums. 

We'll have more detailed discussions in upcoming blogs, and this is a very interesting and important topic that we need to discuss more over time.

Stay interested! Stay focused. Stay curious. Stay dedicated.

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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