Enlightenment from darkness...

It's hard to believe we at Tannin Aquatics have been at this "botanical thing" for almost 4 years now it's interesting to see that we have made a lot of progress in changing minds and attitudes about the art and science of blackwater/botanical-style aquariums. Every day, I see new and exciting work by aquarists from all over the world, and it's incredible!

However, there is still a long way to go, as evidenced by the lingering doubts and misinformation that I still notice in some corners of the internet. There are a number of "myths" about blackwater aquariums which continue to perpetrate, often fielded by self-proclaimed "experts", who's hands-on experience with blackwater, botanical-style aquariums is oddly absent. The propagation of this and other incorrect information just shows that we need to work harder to educate our fellow hobbyists about the realities of these types of aquariums.

One of the biggest myths floating out there is that blackwater aquairums are somehow "dirty" affairs, with tons of decomposing material, clogged filters, and marginal water quality. The dark, soupy water seems to go hand in hand with the perception that these are haphazard, poorly-managed systems, teetering on the bring of some sort of disaster- perhaps the half-mythical "crash" that visits those who tempt the basic rules of aquarium husbandry.

And here's the thing.

I think the very appearance of the tinted, brownish water creates that myth.

As aquarium people, we were pretty much "indoctrinated" from the start of our aquatic "careers" that our tanks should have "crystal clear, blue-white water", and that this is one of the benchmarks of a healthy aquarium.

And of course, I won't disagree that clear water is nice.

I like it, too...However, I would make the case that "crystal clear" water is: a) not always solely indicative of "healthy" or "optimum" , and b) not always what fishes encounter in nature. Think about a body of water like the Rio Negro. This water is of course, "tinted" because of the dissolved tannins and humic substances that are present due to decaying botanical materials.

 We know all about that, right?

Clean water is good. It's important. And that's different from being "dirty", however.

And the color? The tint? It's what's "normal" for this habitat. Although in many hobbyists minds, it isn't. Somehow, we associate anything less than the aforementioned blue-white "clear" water with "dirty."

In a blackwater environment, the color is a visual indicator of an influx of dissolved materials that contribute to the "richness" of the environment. Indeed, a blackwater environment is typically described as an aquatic system in which vegetation decays, creating  tannins that leach into the water, making a transparent, acidic water that is darkly stained, resembling tea.

Despite the appearance, as a general rule, blackwater rivers are lower in nutrients than clear rivers. They have very low concentrations of major ions, such as sodium, magnesium, potassium, and calcium, and lower conductivity and typically low levels of dissolved solids.

Now, in the closed environment that is an aquarium, "stuff" dissolving into the water may have significant impact on the overall quality. Even though it may be "normal" in a blackwater environment to have all of those dissolved leaves and botanicals, this could be problematic in the aquarium if nitrate, phosphate, and other DOC's ("dissolved organic compounds") contribute to a higher bioload, bacteria count, etc.

So, yeah, it boils down to common sense about how we manage our aquairums. And making a mental shift from the mindset that suggests that just because the water is brown, and hosts a lot of decomposing botanical materials, that it's somehow "dirty" or has low quality.

I think we need to contemplate and understand the difference between water "quality" as expressed by the measure of compounds like nitrate and phosphate, and color.

You can have very darkly tinted water (caused by humic substances and tannins), and still have water extremely low in DOC's, nitrate, and phosphate.

Our aesthetic "upbringing" in the hobby seems to push us towards crystal clear water, regardless of whether or not it's "tinted" or not. And think about it: You can have absolutely horrifically toxic levels of ammonia, dissolved heavy metals, etc. in water that is crystal clear and "invisible", and have perfectly beautiful parameters in water that is heavily tinted and even a bit turbid.

That's why the aquarium "mythology" which suggested that blackwater tanks were somehow "dirtier" than "blue water" tanks used to drive me crazy. Color alone is not indicative of water quality for aquarium purposes.

The reality is that many of the wild aquatic habitats from which a lot of our fave fishes come from are anything but "crystal clear." As we know now, the influence of factors like soil, and the presence of terrestrial materials like seed pods, leaves, and branches play a huge role in the chemical composition and appearance of the water. It's really no different in the aquarium, right? Tannins from wood and botanical materials will leach into the water, providing the characteristic "tint" that we've become so accustomed to in our little niche.

It's important, when passing judgement on, or evaluating the concept of botanicals and blackwater in aquariums, to remember this. Look, crystal-clear , blue-white water is absolutely desirable for 98% of all aquariums out there- but not always "realistic", in terms of how closely the tank replicates the natural environment.

The takeaway here is that we should evaluate the "health" or "normalcy" of a blackwater, botanical-influenced aquarium-or ANY aquarium, for that matter- based on it's chemical water quality first and foremost, AND the color of the water on a secondary basis (Keeping in mind, of course, that the "aesthetic" of such an aquarium may indeed mean that the brown water is perfectly normal).

And of course, water quality is very important, and we as blackwater aquarists are as keenly aware about the need for water quality as any other hobbyists out there. This is really no different from the mindset that we've had since our earliest days in the hobby: Common sense. Observation. Diligence. Patience. 

When you have materials of any type breaking down in the aquarium, they are part of the bioload- and that requires an appropriately-sized population of beneficial bacteria and fungi to break down these materials without adversely affecting water quality. We've written about this idea many, many times here in "The Tint", and talked about the "ecosystem" aspect of working with this type of aquarium quite a bit. 

Now, that being said, it would be utterly irresponsible of us to say that you can simply "add stuff" to an aquarium- specifically one that has been in a stable existence for some time- and not be concerned about any impact on water quality. That's part of the reason why we plead with you to go slowly when adding these materials to an established tank, and to test and gauge the impact on your water quality.

Going slowly not only allows you time to react- it gives your bacterial and fungal population the opportunity to grow and adjust to the increased bioload. These organisms can go a long way towards creating a stable, healthy botanical aquarium environment...But they can't work miracles- and they can't do it alone.

And of course, common sense husbandry procedures, like regular water exchanges, use of chemical filtration media (activated carbon, PolyFilter, etc.) give you an added layer of "insurance." A healthy dose of common sense and judgement goes a long way towards a successful outcome! 

The aesthetic is not for everyone...I totally get that.

However, I don't think that we should not simply "give a pass" to the uninitiated hobbyists who make many of the above-referenced assumptions that perpetuate the misunderstandings. We need to educate and explain. Because to simply shrug it off will continue to allow these incorrect myths to intimidate those who want to experiment and explore- and possibly contribute to hobby breakthroughs that will benefit all of us for generations to come!

Stay educated. Stay informed. Stay diligent. Stay original. Stay undaunted. Stay observant. Stay undaunted...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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