On the "down low..."

We talk a lot in our game about "soft, acidic water" and such. Sounds good. Sound a bit scary, even, to some. It requires a bit of preparation. A bit of research. A bit of understanding of water chemistry...

And, when you play in the really low pH zone, you might need to depend upon...Archaens.

Who? Huh?

They sound kind of exotic and even creepy, huh?

Well, they could be our friends. We might not even be aware of their presence in our systems...If they are there at all.

Are they making an appearance in our low pH tanks? I'm not 100% certain...but I think they might be. Okay, I hope that they might be. 

So, WTF are Archaens?


Archaeans include inhabitants of some of the most extreme environments on the planet. Some live near vents in the deep ocean at temperatures well over 100 degrees Centigrade! True "extremophiles!" Others reside in hot springs, or in extremely alkaline or acid waters. They have even been found thriving inside the digestive tracts of cows, termites, and marine life where they produce methane (no comment here)  They live in the anoxic muds of marshes (ohhh!!), and even thrive in petroleum deposits deep underground.

(Image used under CC 4.0)

Yeah, these are pretty freakin' crazy-adaptable organisms. The old sayings that "If these were six feet tall, they'd be ruling the world..." sort of comes to mind, huh?

Yeah, they're beasts....literally.

They're the crew who manage the nitrogen cycle in low pH environments.

Could it be that some of the challenges in "cycling" what we define as "lower ph aquariums" are a by-product of a sort of "no man's land" where the pH is too low to support a large enough population of functioning Nitrosomanas and Nitrobacter, but not low enough for significant populations of Archaea to make their appearance?


I'm totally speculating here. I could be so off-base that it's not even funny, and some first year biology major (who also happens to be a fish geek) could be reading this and just laughing...

Yet, I  still can't help but wonder- is this a possible explanation for some of the difficulties hobbyists have encountered in the lower pH arena over the years? Part of the reason why the mystique of low pH systems being difficult to manage has been so strong?

And then- you think about the pH levels in some natural, well-populated (by fishes!) blackwater habitats falling into the 2.8-3.5 range, you have to wonder what it is that makes life so adaptable to this environment. You have to wonder if this same process can- and indeed does -take place in our aquariums. And you have to wonder if we simply aren't working with these tanks in a correct manner.

Particularly, when they fall into what we'd call "extreme" pH ranges. I wonder if the "crashes" and fears and all sorts of bad stuff we've talked about in the hobby for decades were simply the result of not quite understanding the "operating system?"

I'm kind of thinking so.

Things just work differently at those lower pH levels- in nature, and in our aquariums.

Suffice it to say,  it's not "disaster time" when you get into this range- it just requires greater understanding and a different approach to nitrogen cycle management. Taking the time to learn about the arena in which you're playing. Learning the rules and dynamics, and adjusting your practices to accommodate the requirements dictated by these parameters.

've personally never managed a system with a pH much below 5.5 pH; this is where the "outer limits" of low pH aquariums starts for most, and this is likely the realm of Archaea, as the Nitrosomanas and Nitrobacter barely function at that point. We've seen advanced aquarists depend upon chemical filtration media (such as zeolites) to manage organics at these extremes.

And once again, I think that the real key ingredient (besides knowledge) to managing a low pH system (like any system) is our old friend, patience! It takes longer to hit an equilibrium and/or safe, reliable operating zone. Populations of the organisms we depend upon to cycle waste will take more time to multiply and reach levels sufficient to handle the bioload in a low-pH, closed system containing lots of fishes and botanicals and such.

This certainly gives the bacterial populations more time to adjust to the increase in bioload, and for the dissolved oxygen levels to stabilize in response to the addition of the materials added-especially in an existing aquarium. Going slowly when adding are botanicals to ANY aquarium is always the right move, IMHO. Period. Full stop.

Or, as one of my buddies so eloquently put it during one of those alchohol-fueled fish conference discussions some years back, "The idea is not to kill fish with this shit..." Yup. You don't "dabble" in very low (aquaristically-speaking) pH systems-or any specialized aquatic system, really- without a game plan. Oh, and a pretty good understanding of chemistry- like, way better than what I have. 

Take the experience you've gained in other areas to this new frontier. Use that knowledge to push out further...

Read. Educate. It's out there on the internet. If you want it. You can find it, but it's not always easy to find. Google is a starting point. There are other places to search online, too. Please don't take "the easy way out" and simply email me for some kind of magical answer. I likely don't have one. Really. There isn't one. Knowledge often has to be gained by effort. Your own effort.

And often, experience.

Now, this is the part where you get more annoyed with me, because I offer little more than a challenge. A challenge to study, experiment, and learn. 

So this leaves most of us in a position of doing what we're already doing: Managing our soft, acid (in the "sixes") water aquariums in a manner consistent with good husbandry, going slowly when adding botanicals, and generally testing and observing our fishes. Ours is a world of balancing too much- and not as much as we want- a world of observation, measurement, continuous self-education and experimentation.

We can't be "casual" or "seat-of-the-pants" when we get to the lower pH ranges in the hobby. It's not "set and forget"...Active management is required. We don't enter this arena lightly, or "dabble" in it. I think we are all already aware that each and every blackwater, botanical-style tank requires thoughtful husbandry and a generalized understanding of water chemistry. And taking this body of knowledge and experience to the lower pH arena is a smart move.

There is an extraordinary amount of stuff to learn...And a lot of good source material out there to learn from. Google is your friend. Experience your teacher.

That's the skinny on the "down low..."

Stay brave. Stay undeterred. Stay educated. Stay diligent. Stay curious...

And Stay Wet.


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


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