Have you ever noticed that there are certain things we simply don't like to do as hobbyists?
Like, waiting for stuff. We love "hacks" and shortcuts.
Impatience is, I suppose, part of being human, but in the aquarium hobby, it occasionally drives us to do things that, although are probably no big deal- can become a sort of "barometer" for other things which might be of questionable value or risk. ("Well, nothing bad happened when I did THAT, so...") Or, they can cumulatively become a "big deal", to the detriment of our tanks.
One of the things that I have an issue with in our little hobby sector is the desire by many "tinters" to make use of the water in which the initial preparation of our botanicals takes place in as a form of "blackwater tea" or "blackwater extract."
Now, while on the surface, there is nothing inherently "wrong" with the idea, I think that in our case, we need to consider exactly why we boil/soak our botanicals before using them in the aquarium to begin with.
I discard the "tea" that results from the initial preparation of botanicals- and I recommend that you do, too. Here's why:
As I have mentioned many times before, the purpose of the initial "boil and soak" is to release some of the pollutants (dust, dirt, etc.) bound up in the outer tissues of the botanicals. It's also to "soften" the leaves/botanicals that you're using to help them absorb water and sink more easily. As a result, a lot of organic materials, in addition tannins and humic substances are released.
So, why would you want a concentrated "tea" of dirt, surface pollutants, and other organics in your aquarium as a "blackwater extract?" And how much do you need? I mean, what is the "concentration" of desirable materials in the tea relative to the water? I mean, it's not an easy, quick, clean thing to figure, right?
There is so much we don't know.
A lot of hobbyists tell me they are concerned about "wasting" the concentrated tannins from the prep water. Trust me, the leaves and botanicals will continue to release the tannins and humic substances (with much less pollutants!) throughout their "useful lifetimes" when submerged, so you need not worry about discarding the initial water that they were prepared in.
It's kind analogous to adding the "skimmate" (the nasty concentrated organics removed by your protein skimmer via foam fractionation in your marine aquarium) back into your aquarium because you don't want to lose the tiny amount of valuable salt or some trace elements that are removed via this process.
Is it worth polluting your aquarium for this?
I certainly don't think so!
Do a lot of hobbyists do this and get away with this? Sure. Am I being overly conservative? No doubt. In nature, don't leaves, wood, and seed pods just fall into the water? Of course.
However, in most cases, nature has the benefit of dissolution from thousands of gallons/litres of water, right? It's an open system, for the most part, with important and export processes far superior and efficient to anything we can hope to do in the confines of our aquariums!
Okay, I think I beat that horse up pretty good!
If you want to use the water from the "secondary soak", I'd feel a lot better about that..The bulk of the surface pollutants will have been released at that point. Better yet is the process of adding some (prepared) leaves/botanicals to the containers holding the makeup water that you use in your water exchanges. The materials will steep over time, adding tannins and humic substances to the water.
How much to use?
Well, that's the million dollar question.
Who knows? It all gets back to the (IMHO) absurd "recommendations" that have been proffered by vendors over the years recommending using "x" number of leaves, for example, per gallon/liter of water. There are simply far, far too many variables- ranging from starting water chem to pH to alkalinity, and dozens of others- which can affect the "equation" and make specific numbers unreliable at best.
You need to kind of go with your instinct. Go slowly. Evaluate the appearance of your water, the behaviors of the fishes...the pH, alkalinity, TDS, nitrate, phosphate, or other parameters that you like to test for. It's really a matter of experimentation.
I'm a much bigger fan of "tinting" the water based on the materials in the aquarium. The botanicals will release their "contents" at a pace dictated by their environment. Of course, you can still add too many, too fast, as we've mentioned numerous times. It's all about developing your own practices based on what works for you.. In other words, incorporating them in your tank and evaluating their impact on your specific situation. It's hardly an exact science. Much more of an "art" or "best guess" thing than a science..at least right now.
And the "tea" thing?
If you're doing it and you're happy with the results, I can't argue with that. I can only tell you that I personally wouldn't do it that way. At least, not without trying to control as many variables as possible.
But then again, I'm the guy telling you to toss in leaves and botanicals in your aquarium...and not really giving you "x" amount per gallon or whatever...just telling you to "go slowly, observe and test."
Yeah, there is so much we need to learn...So much that we still don't know; and we are operating on pure "gut instinct."
And perhaps that's not such a bad thing.
Keep studying. Keep experimenting. Keep tweaking. Keep observing.
Stay creative. Stay diligent. Stay consistent. Stay on top of things...
And Stay Wet.