It is really cool to hear from so many hobbyists who are embarking on this new foray into the world of aquatic botanicals, blackwater, and a more natural aesthetic. And with all the neat pic of up-an-coming tanks and hearing about your exciting new projects, we get some interesting questions...and I realize that, even though people have been adding leaves and cones and seed pods and such to aquarium for years, no one really ever made the effort to aggregate the experience; to become a destination for the "state of the art", etc. in this arena. Well, we're happy to fill that role in what one of my (very critical, I might add) fishy friends reluctantly admitted is becoming (in his words) "a global movement."
As such, there are a lot of topics within the realm of botanical-influenced aquariums which need to be addressed, and as more and more of you get into these types of tanks, you're working on cool solutions and technique to address them and make our lives easier. One of the questions that we get a lot concerns the concept of water movement in a botanical-influenced aquarium- like, how much we need, what it does to these types of tanks, and what the best way to approach it is.
Water movement is a very important and (no pun intended) dynamic topic. In the freshwater world, apart from hobbyists who keep fishes like Hillstream Loaches and other fishes known to benefit from strong water movement, we don't really think about it all that much. However, with the advent of tanks field with stuff like leaves and seed pods, it's something to think about, both from the point of view of its impacts on the aesthetics and environment of the aquarium.
I'm a big fan of fairly vigorous water movement in almost any aquarium. I think it's my "reef" orientation, but it works for a variety of fishy applications! Now, I realize that certain fishes (Anabantoids and killifishes come to mind; there are others) hail from environments that we would almost label as "stagnant", and flow in the "aquarium sense" is really not an issue. However, for the majority of fishes that hail from botanical-influenced, blackwater environments, water movement is still an important and, in my opinion, necessary consideration.
In wild environments, such as the Amazon River, water flow is variable, ranging from moderately strong in major tributaries, to barely palpable in flood plains and igarapes, which meander through the forest. In the rainy season, currents increase as water levels increase. In the dry seasons, obviously there is less water, and less water movement. There have been a lot of studies related to the transport of nitrogen and phosphorus in Amazonian streams, much related to the impact of deforestation. Suffice it to say, movement of water is important in distributing, diluting, and processing nutrients in these streams, and it's much the same in aquariums.
Water movement is like a refreshing breeze on a warm day, a vital part of the closed system dynamic, IMHO. It offers even distribution of temperature, nutrients, and oxygen. It also provides a bit of "exercise" for your fishes, which swim against some of the currents you create. Water movement has long been considered a key part of the nutrient export process in closed system aquaria.
In our botanical-influenced tanks, with lots of leaves and such, we obviously have to consider that strongly directed flow from the outlets of pumps, powerhead, and filters can push stuff around- annoyingly so! Leaves, in particular, are subject to the "whims of water movement" because of their light weight and buoyancy. Despite the potential for disruption of your leaves and such, it only makes sense that you should direct flow into the aquarium to be as widely distributed as possible. In my experience, it is important to put a little flow down to the bottom, if only to keep debris from accumulating significantly where your botanicals are (particularly if you're like me and keep a lot of leaves in there).
Directing some flow towards the bottom not only helps evenly distribute dissolved oxygen throughout the system- it keeps the pH from becoming "stratified", and helps prevent pockets of stagnation, particularly in thick leaf litter beds, which can lead to a lot more algal growth and biofilms than you'd like to see! Just to reassure you, I've found that, as leaves and botanicals become more saturated and start to break down, they tend to "wander" less from their original positions in the aquarium. And, if you're like me, and promote and "active" or "dynamic" leaf-litter management approach as part of your regular maintenance activities, you're continuously adding (and occasionally, removing) leaves to keep the system "refreshed" and deriving optimum levels of tannins that keep the visual "tint" you want.
And, for that matter, it could be argued that this process of "managing your leaf litter" (yeah, can you believe it's come to THAT?) will help maintain a greater biological and chemical stability. My office blackwater system, for example, runs with a surprisingly stable pH around 6.6, and stays within a tight range. More experimentation, observation, and monitoring is obviously necessary in order for us to state categorically that chemical stability is derived from this process, but the anecdotal observations seem to point strongly towards this hypothesis being at least somewhat correct. This process is perfectly analogous with what happens in nature, where leaves are regularly falling into the waters, others are decomposing and being "processed" either by breaking down completely, or moving downstream.
As you can tell from my rather unscientific treatment here, the topic of water movement- and, for that matter, the topic of overall management- in blackwater, botanical-influenced aquariums is still evolving, and there is a LOT of room for experimentation, observation, and development of technique. This, in my opinion, is the most exciting part of the "New Botanical" movement we're participating in: It's "open source", with all sorts of new things being learned each and every day. We've made a lot of progress- identifying some basic practices to help ensure a good start, and making observations about the potential pitfalls and perils as well. And of course, we're developing, practicing, and refining techniques to hone our husbandry skills and create better, more stable environments for our precious fishes.
And the best part? We're doing it together, without arrogance, conflict, and attitude. We're just fish geeks, united by a particular interest (albeit an odd one to some people), and having a hell of a good time doing it! Everyone's input is valued- and important!
Stay engaged. Stay observant. Stay humble. Stay interested. Stay generous.
And Stay Wet.