The strange phenomenon of "cyclical" occurrences..."Quirks", processes, and mental shifts...

The world of botanical-style aquariums is a very dynamic one, isn't it? It's a world of constant change; continuous biological processes, and aesthetic variations on a weekly basis. As lovers of botanical-style natural aquariums (blackwater, brackish...whatever...) we have learned to be most tolerant of stuff that would likely drive many hobbyists who subscribe to more "mainstream" approaches absolutely freakin' crazy, right?

Yeah, I think so.

We have an enormous tolerance for tinted water, decomposition, biofilms, and other stuff that is really rather contrary to what we've been brought up in the aquarium world to be considered "okay" or "acceptable..."

And our botanical-powered aquariums have their own unusual, if not endearing- attributes, don't they?

Let me explain. You've likely noticed this phenomenon over the years in many different types of aquariums.

Ever noticed that aquariums seem to go in "cycles", and display certain "quirks" in their function?

For example, some tanks will enjoy periods of time where the fish and plants are actively growing, the water is crystal clear, unwanted algal growth is minimal, and everything seems to be "spot on."

And then, seemingly inexplicably, after months or perhaps years, the tank may not look "quite as good" for several weeks, only to rebound to its former glory with minimal to no intervention on your part in a matter of a day or two...


I think we've all experienced this in planted tanks before- and likely in other systems, too. Odd "cycles" that create changes that you just can't quite put a finger on before they "correct" themselves... 

We have found that some of these cyclical occurrences in planted tanks, for example, might be due to nutrient variations, trace element depletions, growth of plants or algae, etc.

Over the years, I've experienced certain "quirks" with blackwater/brackish botanical-stye aquariums. This is particularly noticeable to those of us who, like me, love keeping our systems set up over very long terms without disturbing them or breaking them down.

As I wrap up the journey of our office brackish water aquarium, I can look back on the aquarium's operation, and perhaps give us some interesting perspective based on our experiences with it over the time it has been in operation.

In particular, once of the things I've noticed in general in botanical-style aquariums, field with leaves, botanicals, sediments, and wood, is that the water will take on a bit of "cloudiness" from time to time, almost as if it's been "dosed" with some sort of materials which make it a bit turbid- even with excellent husbandry techniques.

I noticed this in the  brackish-water system a lot, particularly in its earlier phases.

I think there are a few explanations, one of which is the fact that there is a gradual, yet cumulative decomposition of organic materials from within the botanicals themselves. Maybe it's substances within the wood or botanicals you're playing with. Stuff like lignin, etc., which seeps into the water column as the materials break down, exposing new layers of their tissues to the aquatic environment.

Some of it could simply be fishes disturbing layers of substrate or even decomposing materials. It could even be some bacterial blooms- again, brought about by the aforementioned botanicals.

Yeah, it sounds kind of bad...

Is it? Does it affect our fishes? More often than not, it has no real impact on their health, in my experience.

It arrives...and reaches a sort of "peak..."

And then- it usually just goes away just as mysteriously as it comes...

And of course, as a lifelong aquarium hobbyist, when you see stuff like "cloudiness", you first start looking at overall water quality, stocking, feeding habits, and husbandry technique. I am a fanatic water quality guy, being a reefer,  and I'm a devoted tester and water exchange fanatic.

Is it possible that my feeding or technique could have caused this? Maybe, but not likely. I'm stupidly careful...Like, dispensing each piece of frozen food with a toothpick careful. My tanks are environmentally stable, have little to no detectable nitrate, barely detectable phosphate, and receive regular water exchanges.

And, as a rule, I stock my aquariums lightly.

Okay, so right there, I apparently eliminated the "usual suspects", huh?

However, arrogance aside- it IS possible, right?

The idea of a "bacterial bloom" is certainly possible. Sure.

However, is this bad?

Not always, IMHO. 

Perhaps the specific materials we use have a direct impact on the appearance of this "cloudiness."

Now, interestingly, I utilize mangrove wood in both my home blackwater and brackish water aquariums a lot, and I'm of the belief that this is a beautiful type of wood, but it's very "dirty" from a standpoint of materials contained within the tissues of the wood. Both types of systems experienced an initial "haziness", which I hadn't seen to the same extent with other botanical systems I've played with which utilized different types of wood.

Coincidence? Perhaps.

I mean, every botanical tank seems to acquire a certain "patina" (one of my blackwater-enthusiast friends calls it "flavor"), which impacts the overall appearance of the system. And we do throw all sorts of seed pods, leaves and other stuff into our tanks- a perfect "cocktail" for unusual water conditions, huh?

And, let's face it- some materials are simply more "dirty" than others. Now, "dirty" doesn't necessarily mean "dangerous" or "bad"- it simply means that it will impart a unique set of characteristics to the aquatic environment and that you need to monitor your aquarium carefully.

Nothing really new or unexpected there, right?


And ultimately, the "cloudiness thing" just sort of goes away, yielding that sparkling brown clarity that we love. Sure, some activated carbon and stuff like Poly Filter help, but I think the biggest  factor is...time. Just being patient.

This is not entirely inconsistent with the characteristics we see in Nature. Wild habitats, such as flooded forests, frequent have a level of turbidity in the water that is quite apparent, yet seemingly of little impact to the fishes which reside there. Now, I realize that aquariums are not open, natural systems; however, they are impacted by most of the same processes, aren't they?

The other random factor in our version of the botanical-style brackish aquarium is the use of very rich, mud-influenced soils in the composition of the substrate we play with. I think some of the material leaches into the water column on occasion. Add this to the equation, and with the occasional burrowing activities of the snails we employ, and with the significant water movement provided by electronic pumps, and this is another factor which can affect water clarity.

Of course, it's kind of a no-brainer that silty, richly-sedimented substrates will impart a certain degreee of cloudiness to the water until these materials settle out over time. We've seen this in many of our freshwater "igapo" experiments, so there is nothing unique to brackish in this regard.

And perhaps it's also the inclusion of the mangroves themselves, and the epiphytic organisms which live on and among their roots and propagule structures?

The other quirk we all experience from time to time is the accumulation and dissipation of biofilms and occasional biocover on our botanicals.  This is simply considered "par for the course" with botanicals, isn't it? Yet, I know many hobbyists (myself included) who have run tanks with minimal biofilm over their botanicals at almost every phase of the tanks existence.  

Why is this? 

Who the hell knows, right?


There are SO many possible variables in what we do that it's almost impossible to generalize! We can only tell you that it happens, and that it is essentially harmless and often subsides somewhat over time.

"Gee, that was pretty damn helpful, Scott."

Hey, man- I don't have all the answers. I simply don't know how we can look at all of the variables that impact the way these tanks function and arrive at some sort of general conclusion about why.

Suffice it to say, we may simply have to treat every tank as a unique microcosm, to which some generalized processes will occur. However, each system simply behaves differently from others, making it near impossible- or at the least- irresponsible- for us to generalize about what causes it, how long it lasts, and what impacts it has on the aquarium's environmental parameters.

Some hobbyists have experienced "bursts"of biofilm which accompanies the addition of every batch of botanicals to an aquarium. In our community, we take the "waxing and waning" of biofilms in our tanks as a sort of "right of passage", and have come to expect and tolerate the stuff- particularly in a newer aquarium, with less mature nutrient export processes.

Learning to accept this was, and still is- a big part of the "mental shift" hobbyists have to make when transitioning to this type of aquarium from a more "conventional" one.

Accepting that decomposition, change, and the transformations of hardscape materials by fungal and bacterial action are simply "part of the game" is pretty fundamental. Again, we advocate not continuously intervening in these natural processes, which allows the aquarium to find its own biological balance (for want of a better word). It seems obvious to all who play with these systems that, as your tank matures and becomes more biodiverse, it most definitely "evolves" to some extent...

Despite the rather unusual aesthetic.

Oh, but that biofilm and turf algae and fungal growth really gets to some people!

Left alone, it almost always seems to dissipate in just a few weeks. And occasionally, you'll see a covering of biofilm or turf algae crop up on botanicals which have been submerged for some period of time, seemingly without reason. 

These occasional "outbursts" by the biofilms may disappear as quickly and mysteriously as they appear, without any apparent correlation. Or do they? Well, there must be SOME explanation! 

And of course, as we know, everything occurs in Nature (and our tanks) for a reason...And the searching for answers and trying to figure out the "hows and whys" of our unique aquariums has been a real delight for me.

Nature- and our tanks...are ruled by cycles. Seasonal? Biological? All types. Something we haven't thought a lot about in aquarium keeping (except for the nitrogen cycle, of course).  We are playing with "wet" and "dry" season simulations. I'm convinced that these will yield some interesting insights on the function of closed aquatic systems and how they react to changes of all sorts.

Cycles and quirks.

Yeah, "quirks!"

The undeniable "quirkiness" of a blackwater/brackish, botanical-style system is one of the most enjoyable facets of this type of approach. It's a constant evolution and a tremendous thing to witness firsthand.

Yes, they're filled with quirks.

However, botanical-style aquariums are filled with a certain something..A "mystery", a "vibe",  a "romance", if you will. A unique operational "structure", which separates them from what we have come to expect as "normal" for aquariums over the decades...

And that "something" is what keeps many of us coming back for more- "quirks", "cycles" and all!

Stay diligent. Stay excited. Stay devoted. Stay experimental. Stay patient. Stay observant...

And Stay Wet.


Scott Fellman

Tannin nAquatics 


Scott Fellman
Scott Fellman


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