Just, like...maintain...okay?

We receive a lot of questions about the maintenance of botanical-style aquariums. And it makes a lot of sense, because the very nature of these aquariums is that they are stocked, chock-full of seed pods and leaves, all of which contribute to the bio load of the aquarium- all of which hare in the process of breaking down and decomposing to some degree at any given moment.

It's not so much if you have to pay attention to maintenance with these tanks- it's more of a function of how you maintain them, and how often. Well, here's the "big reveal" on this: 

Keep the environment stable.

Environmental stability is one of the most important- if not THE most important- things we can provide for our fishes! To me, it's more about doing something consistently than it is about some unusual practice done once in a while.

Like, ya' know- water exchanges.

Obviously, water exchanges are an important part of any aquarium husbandry regimen, and I favor a 10% weekly change. Iit's the regimen I've stuck with for decades, and it's never done me wrong. I think that with a botanical influenced aquarium, you've got a lot of biological material in there in addition to the fishes (you know, like decomposing leaves and softening seed puds- stuff like that), and even in well-managed, biologically-balanced aquarium, you still want to minimize the effects of any organics accumulating in a detrimental manner. 

This piece is not really about water changes, and frankly, you can utilize whatever schedule/precentage works for you. The 10%-20% weekly has worked for me; you may have some other schedule/percentage. My advice: Do what works for you and adjust as needed.

Just do something.

Another question that we hear all the time around here is wether we should let the leaves in our tanks remain as they decompose completely, or remove them after they begin to break down.

Depending upon my "mood de jour", I may elect to keep leaves and botanicals in my system until they completely decompose. Ing an otherwise well-managed aquarium, this is generally not a water-quality-affecting issue, in my experience, and is more a matter of aesthetic preferences. There are times when I enjoy seeing the leaves decompose down to nothing, and there are other times when I like a "fresher" look and replace them with new ones relatively soon.

Some individual leaves and botanicals "recruit "an inordinate amount of biofilms, which even I may find distracting (hard to believe, I know...), so I will typically remove those "offenders". Again, no harm in leaving them in; the presence of biofilms indicates the presence of beneficial bacteria just doing their thing. It's just that sometimes, you don't want them doing too much of their thing- or in a place where you have to look right at it every day! You can remove sections of it with a planting tweezer (tedious, but oddly relaxing and satisfying, I might add), or a siphon. Of course, as mentioned above, you can just yank the offending botanical right out of the tank and be done with it, too!

When leaves and botanicals break down completely, you end up with a fair amount of "stringy fungal growth, biofilms, and fine particles of decomposed leaves that tend to accumulate here and there in healthy aquariums.

What's cool about this stuff is that, not only do you see it in aquariums- you see it extensively in natural ecosystems, such as Amazonian streams, Asian peat swamps, and other habitats.

Of course, in the case of a "botanical" style aquarium, It's an integral component of  what we call an "enriched" substrate. As botanicals break down- just like in Nature- they create a diverse matrix of partially decomposing plant materials, pieces of bark, bits of algae, and some strings of biofilm.

Ahh, "detritus..."

Stuff that sounds diverse, and it's also benign. Of course, in the aquarium hobby, it's all classified as "detritus." Detritus seems to have a bit more of a sinister connotation to it. 

The definition is a bit more precise:

"Detritus is dead particulate organic matter. It typically includes the bodies or fragments of dead organisms, as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose or remineralize the material." (Source: The Aquarium Wiki)

Well, shit- that sounds bad! 

It's one of our most commonly used aquarium terms...and one which, well, quite frankly, sends shivers down the spine of many aquarium hobbyists. And judging from that definition, it sounds like something you absolutely want to avoid having in your system at all costs. I mean, "dead organisms" and "fecal material" is not everyone's idea of a good time, ya know?

Literally, shit in your tank, accumulating. Like, why would anyone want this to linger- or worse- accumulate- in your aquarium?

Yet, when you really think about it and brush off the initial "shock value", the fact is that detritus is an important part of the aquatic ecosystem, providing "fuel" for microorganisms and fungi at the base of the food chain in aquatic environments. In fact, in natural blackwater systems, the food inputs into the water are channeled by decomposers, like fungi, which act upon leaves and other organic materials in the water to break them down. 

And the leaf litter "community" of fishes, insects, fungi, and microorganisms is really important to these systems, as it assimilates terrestrial material into the blackwater aquatic system, and acts to reduce the loss of nutrients to the forest which would inevitably occur if all the material which fell into the streams was washed downstream!

That sounds all well and good and well, grandiose, but what are the implications of these processes- and the resultant detritus- for the closed aquarium system?

In years past, aquarists who favored "sterile-looking" aquaria would have been horrified to see this stuff accumulating on the bottom, or among the hardscape. Upon discovering it in our tanks, it would have taken nanoseconds to lunge for the siphon hose to get this stuff out ASAP!

In our world, the reality is that we embrace this stuff for what it is: A rich, diverse, and beneficial part of our microcosm. It provides foraging, "Aquatic plant "mulch", supplemental food production, a place for fry to shelter, and is a vital, fascinating part of the natural environment. 

It is certainly a new way of thinking when we espouse not only accepting the presence of this stuff in our aquaria, but actually encouraging it and rejoicing in its presence! 


Well, not because we are thinking, "Hey, this is an excuse for maintaining a dirty-looking aquarium!"


We rejoice because our little closed microcosms are mimicking exactly what happens in the natural environments that we strive so hard to replicate. Granted, in a closed system, you must pay greater attention to water quality, but accepting decomposing leaves and botanicals as a dynamic part of a living closed system is embracing the very processes that we have tried to nurture for many years.

And it all starts with the 'fuel" for this process- leaves and botanicals. As they break down, they help enrich the aquatic habitat in which they reside. Now, in my opinion, it's important to add new leaves as the old ones decompose, especially if you like a certain "tint" to your water and want to keep it consistent.

Not only does adding new leaves keep the water tint (and parameters, once you dial 'em in) consistent, it also gives you a sort of "evolving" aesthetic, which is similar to what you'll see in Nature: newly fallen leaves replacing older ones that have decomposed. Botanical system can be very dynamic in this way!

And then, there's that whole "water color" thing...

Like many of you, I store my water in plastic containers for use during water changes. Over the years, I've sort of worked out a rough "formula", if you will, to create consistent "tint" and conditions for my makeup water. Typically, I'll add 3 medium-sized Catappa leaves to a 5 U.S. gallon container of RO/DI water. This has always given me a nice even color and a pH around 6.5-6.6, which is the range I maintain in my display aquariums.

Hardly an exact science, I know.

Now, "your mileage may vary" as they say, and perhaps a different number of leaves in a different sized container works for you. Obviously there are many variables, even in as simple a practice as steeping leaves in your makeup water, like the source of the leaves and their "potency" (in regard to tannins contained in their tissues), the age and condition of the leaves, temperature, etc., etc., etc.

Oh, and then there's that recommendation to test your water. Yeah, that's me. And you don't need to go crazy, but regular tests of pH, alkalinity are really important when you're flirting with soft, acid water systems. And checking phosphate and nitrate are never a bad thing, as they can give you an insight into trends within your system, as well as just good old-fashioned knowledge about how your system tends to operate once it settles in.

Although it IS possible to have too much information (to the point where you can obsess over what are really insignificant details), it's never a bad thing to have enough to spot trends, right?

People ask a lot if blackwater tanks are tricky to maintain, given the reputation for challenges in low pH, soft water systems and the more delicate fishes traditionally associated with them (like Discus and Wild Angelfish, etc.). Honestly, I don't think they are any more "difficult" to care for than any other type of aquarium.

Definitely easier than say, a Rift Lake cichlid tank- and a magnitude easier than a full-blown reef system (or coral propagation facility, as I can attest to!). Like anything else, you'll develop the techniques, skills, and systems to manage your system in a manner that works for you and your fishes- and that's really all you need to do, in my opinion!

Observation- just looking at your fishes and their aquariums- goes a long way towards success in ANY type of aquarium. With hobbyists busier than ever before, with more personal and other demands vying for attention, this obvious thing may not be as easy as it used to be- so make it a point to spend some time every day just looking at your aquarium.

The longest I've personally maintained such a system has been about 5.5 years, and the only reason I broke down that aquarium was because of a home remodel that required the removal of everything from the space in which the aquarium was located. I set it up again shortly after the work was completed. The reality, though, is that I could have kept this system going indefinitely. 

As most of you who work with these aquariums know, the key to long-term success with them is to go slowly, deploying massive amounts of patience, common-sense husbandry, monitoring of environmental parameters, and careful stocking management. Not really much different from what you'd need to do to successfully maintain ANY type of aquarium for the long haul.

Yeah, real "news flash" there, right?

So, it all starts with the way these tanks "run in", and that will sort of "set the tone" for the care and long-term maintenance involved. 

Expectations, if you will.

First off, one of the things that we all experience with these types of systems is an initial burst of  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, this tint will be more pronounced and likely last longer than if you're actively removing it with these materials! And, if you use too much carbon, you'll be one of those people who emails me with a starting line like, "...and I added an entire package of catappa leaves and my water is barely tinted..."

You might also experience a bit of initial cloudiness or turbidity...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.

Oh, and the reality is that in a tank with lots of botanical materials, the water may not always be "crystal clear." I mean, sure it'll be clear- as in, you can see across it- but it might have a sort of "soupy" look to it. This is for the very reasons stated above. Mental shifts required...

So, that being said...what happens next?

Well, typically, as most of you who've played with this stuff know, the botanicals will begin to soften and break down over a period of several weeks. Botanical materials are the very definition of the word "ephemeral." Nothing lasts forever, and botanicals are no exception! Pretty much everything we utilize- from Guava leaves to Melostoma roots- starts to soften and break down over time. Most of these materials should be viewed as "consumables"- meaning that you'll need to replace them over time.

I'll backtrack and touch on that whole idea of "leaving stuff in" to break down fully.

I have never had any negative side effects that we could attribute to leaving botanicals to completely break down in an otherwise healthy, well-managed aquarium.

Many, many hobbyists (present company included) see no detectable increases in nitrate or phosphate as a result of this practice. Of course, this has prompted me to postulate that perhaps they form a sort of natural "biological filtration media" and actually foster some dentritifcation, etc. I have no scientific evidence to back up this theory, of course (like most of my theories, lol), other than my results, but I think there might be a grain of truth here!

So, the living with your botanical-style backwater aquarium isn't just about a new aesthetic approach. This is where the "mainstream aquarium crowd" (LOL) gets it all wrong and really "short-sells" this stuff... 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, yeah, playing hunches- all skills that we as hobbyists have practiced for generations.

When you distill it all- we're still just "keeping an aquarium"-but one that I feel is a far more natural, dynamic, and potentially game-changing style for the hobby.

So, relax, observe, and...just maintain. Your aquarium will be fine.

Stay diligent. Stay consistent. Stay aware. Stay involved...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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