Zen and the art of blackwater maintenance..

With this obsession we have for blackwater, botanical-influenced aquariums burning in us for years, and with (apparently) an equally obsessive interest in many of you, the topic of long-term maintenance of these types of aquariums comes up more frequently. No longer a "side show" sort of aquarium, blackwater tanks are becoming just another type of aquarium we work with, and techniques for managing them are being refined continuously!

Okay, let's be clear about one thing: There really is no "magic technique" to maintaining a blackwater, botanical-influenced aquarium, other than the usual "stuff"- with a few variations. The "mantra" I practice in ANY aquarium I maintain is "SPS" ("stability promotes success") that a reef keeping friend has proffered for many years. I personally think that 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.

Obviously, water exchanges are an important part of any aquarium husbandry regimen, and I favor a 20% weekly change. That may seem like a lot to some, but it'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 20% weekly has worked for me; you may have some other schedule/percentage. My advice: DO what works and adjust as needed. 'Nuff said.

Depending upon my "mood de jour", I may elect to keep leaves and botanicals in my system until they completely decompose. 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!

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 different aesthetic frequently, 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!

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 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.

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.

From a filter media standpoint, I think we've covered this before, but I am a big fan of Seachem "Renew", which is known as an "organic scavenger resin", which is formulated specifically to remove the undesirable stuff (like ammonia, nitrates, phosphates, etc.) from you water without taking out the tannins and color we work so hard to accumulate! I wrote about this stuff in detail in an edition of "The Tint" last week.

And of course, you could always use activated carbon in a botanical-influenced tank and get many of the aesthetic benefits, simply without the tint. If an organic scavenger resin is the filter media equivalent of a "smart bomb", then activated carbon is a polar opposite- as undiscriminating about what it picks up as a tourist at a cheap hotel buffet, if you know what I mean! It takes out a wide range of pollutants, discoloration, organics, trace elements, 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 insights gained from this pleasant practice are almost too great to mention. Yet, you'd be shocked at how many advanced aquarists with a lot of tanks don't do this, simply because they don't have time for it in their daily schedules. I say, make it a part of whatever daily routine you follow! Make the time- it's worth it for you- and for your livestock.

Okay, that's kind of it for now. I think we more-or-less touched on the finer points of the "art" (an it's an "art" as much as it is a science) of the maintenance of blackwater/botanical-influenced aquariums. I'm pretty sure you've developed some of your own methodologies, techniques, and ideas about this game, so feel free to share!

Stay tinted! Stay focused. Stay consistent.

And Stay Wet.

Scott Fellman

Tannin Aquatics


Scott Fellman
Scott Fellman


4 Responses

Scott Fellman
Scott Fellman

August 24, 2020

Hi Helene,

Glad you enjoyed..>Also wrote new piece just the other day…Check it out!



August 23, 2020

Hi Scott, i wrote to you on Messenger about maintenance. I enjoyed reading this article. Looking forward to a new Podcast. Cheers from Canada!

Scott Fellman
Scott Fellman

October 16, 2019

Hi there!

Thanks for the kind words! Looking forward to seeing your tank become a success!


Shankar Mani
Shankar Mani

October 13, 2019

Hi Scott,

Very insightful and interesting read.
I’m into the hobby for a couple of decades and am inspired by your articles on black/biologically influenced aquariums.
Wish me luck as I’m going in for a 300g black water aquarium for wild altum and geophagus.
Thank you.
Staying wet and confident.

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