As you probably imagine, we receive a lot of correspondence here at Tannin about a myriad of topics. It's one of the coolest thing about being in business...or, as one of our customers asserted recently, a "thought leader."
One of the questions we receive a lot around here usually starts out something like this: "I really like the idea of a blackwater aquarium. I'm starting up a 50 gallon (200 L) aquarium, and I want to use a bunch of botanicals along with a big piece of Mopani wood, and..." The email typically ends with, "How many ______ do I need"
Wow. That is actually a really tough question, isn't it? I mean, there are a ton of factors to consider when utilizing botanicals in an aquarium. Most notably, stuff like just how much "coverage" you want in the tank with the botanicals. In the case of leaves- how many do you want to see? How dark do you want your water? The immediate response I generally give is, "What kind of fishes are you into? How "full" do you want the display to look? What type of effect are you trying to achieve? And what part of the world are you interested in replicating?"
The fact of the matter is, fishes from blackwater environments encompass many different families, not just the obvious Tetras, dwarf cichlids, and catfishes.
The interesting thing is botanical materials are found in pretty much every body of water that fishes live in. Even swift-moving streams have branches, leaves, and the occasional seed pod or two in the mix.
Most of our "variety packs" have been created to give you a "baseline" group of botanicals to give decent coverage for task up to about 30-50 US gallons ( approx. 113-189 L), yet the variables, as briefly outlined above, are so numerous that it makes such "stocking levels" debatable at best.
From an environmental standpoint, adding a lot of material to your tank could increase it's boiled, as these botanical materials start o break down..so adding a lot of stuff at once to an already established tank is not the best idea. Slow is better...
You could always purchase more stuff than you initially need, as botanicals should be looked at more or less as "consumables", needing replacement as they break down over time. This will not only keep the aesthetics where you want them, but in the case of leaves and cones, will help keep water parameters (ph mainly) more consistent over time.
People ask about how many leaves or botanicals it would take to drop the pH in their tank, and that is yet another one of those "It depends" questions...Many factors, such as the starting pH and general hardness of the water influence this. Being natural materials, botanicals are not like an additive where "x" number per gallon could bring down your pH by a factor of ".1" or whatever...
Also, many of the botanical materials we offer may tint the water, but have minimal affect on pH, particularly in hard water. The leaves and many of the palm and cone products, on the other hand, have much more "proven" capabilities in this area. Again, the best advice on this is to go slow, test, and see what works for you.
In the end, how much to add is largely dictated on aesthetics and your aquarium's current status. If your starting a brand new tank, of course you could add everything at one time after preparation...my advice is to do some basic water chemistry monitoring as you would in any situation, of course.
As we've stated many times here and elsewhere, the idea of adding botanical materials to aquariums is certainly not a brand new one. However, the idea of coupling aesthetic, environmental, and utilitarian benefits together as a result of using them is an evolving process...one in which everyone's input and experience is valued and necessary!
Today's simple thought on an emerging, and rather complex subject.
Stay curious. Stay generous. Stay creative.
And Stay Wet!