Our obsession with utilizing leaves in our aquariums has led us to experiment with so many different types over the years. One of the more recent additions to my personal "rotation" has been the lovely Magnolia leaf. It's interesting not only from an aesthetic perspective, but from a function and utility one, as well.
Unlike virtually any other leaf we offer here at Tannin, Magnolia has an allure and a usefulness that make working with it worth putting up with "some stuff..."
More on that "stuff" later.
Now, talk about an interesting leaf! The genus Magnolia has over 200 members, distributed all over Asia, the Americas, and the West Indies. It's an incredibly diverse, beautiful genus of trees.
And yeah, the leaves great to use in aquariums!
For our purposes, of course, it was important to see if the leaves were safe with fishes before we even considered using them in our aquaria, let alone, offer them for sale! And naturally, when I first started playing with them years ago, I'd see all sorts of "information" on them online.
Yeah, if you troll online forums, you'll see the full gamut of opinions and discussions, ranging from "They f ---ing killed my Apistos!" to, "I've used them for decades without any issues!" The reality is, that like almost any botanical or plant material used in an aquatic setting, if you obtain them from a pollution/pesticide-free source, prepare them, clean them, and add them gradually to your aquarium, you really shouldn't have any issues.
Ahh, but I digress. More on that later.
First off, the species we're typically using here in the United States is Magnolia grandiflora, and it's a beauty! They can vary widely in color, including oranges and browns, which makes them particularly attractive for a leaf litter bed! There are over 50 cultivars of this species alone, so without being a full-on botanist, let's assume that, at least superficially, they are all more-or-less the same for our purposes. (I can hear my college Botany professor cringing right now...LOL)
Morphologically, Magnolia leaves have a pretty distinctive look. Let's just say that, when you remove them from the context of the decidedly "non-tropical"-looking tree, they're downright "exotic-looking", and perfect for our uses! They are rather heavy leaves, which is great news, because it means they'll last a lot longer in a submerged state, meaning that you don't need to replace them as often as you would, say, Catappa or Guava.
Magnolia leaves have a waxy coating which renders them more resistant to damage from salt and pollution. I'm going out on a limb and hypothesizing that it's this "waxy coating" that might be the source of some of the concerns we have heard about using these leaves in aquariums. The covering on the leaves is called the "cuticle". It is composed of cutin, a wax-like material produced by the plant that is chemically a "hydroxy fatty acid."
The purpose of this covering is to help the plant retain water and repel pollutants. And you only see it on the top surface of the leaves, interestingly...Makes sense, right? it's the side that faces the elements, so...
Magnolia grandiflora produces phenolic antimicrobial chemicals, compounds called coumarins and sesquiterpene lactones, which discourage predation and grazing by terrestrial insects. Coumarins have known anti fungal properties. I can't help but wonder if these same antimicrobials and antifungals might-might provide some sort of benefits to fishes in a similar fashion to those found in Catappa.
However, this is just conjecture on my part; I am not aware of any scientific study on the matter, nor of the existence of data to confirm this theory. That being said, I am also not aware of any known fish toxins or other harmful chemicals present in these leaves.
Now, can we assume that they are safe for fishes, which would be continuously exposed to anything leaching from the leaves in the aquarium? No. Of course not. We can't ever assume anything in the hobby, right?
You can kill your fishes with any botanicals- or virtually anything- that you add to your aquariums.
However, in almost a decade of personal use, and years of similar experience of a number of long-term users of these leaves (whom I trust and know to be highly competent aquarists keeping many varieties of fishes), we have experienced no fish losses that can be attributed directly to the use of carefully sourced and properly prepared Magnolia leaves.
In my opinion (and based on the above experience of myself and others), the real "danger" to fishes of these leaves would be from external pollutants (soot, garden chemicals, and other surface pollutants that would accumulate on the leaves), rather than any particular issue caused by the leaves themselves. However, this doesn't mean that you should just toss them in your tank!
Like any botanical, you should take the time to rinse, and really, soak the leaves overnight in (initially) warm or recently boiled water. This will help remove any residual surface contaminants and pollutants that may be present on leaves.
Add only a few at a time to gauge the results, like you would with any type of leaf or botanical.
And yeah, of course, you can collect these leaves yourself. I have to digress just a bit when I discuss natural materials which are commonly available in many parts of the world...And, I always get a bit "amped up", because there's always someone out there who loves to shout that they have a Magnolia tree in their yard or whatever, and that "..it would be foolish to pay for these leaves", blah, blah, blah.
Well, yeah. No shit.
I mean, if I had a Jackfruit tree in my yard, I'd collect my own, too. Duh.
If you have a source for free, don't pay us to obtain them! It's that simple. There's no mystery here. Ours are not magic. We don't hide the fact that they can be collected easily if you have some in your area! However, if you live in North Dakota, New York City, Reykjavik or Munich, or another place where these trees are not native, you can certainly purchase them from us, or some other vendor out there.
Of course, if you're going the route of collecting the leaves yourself for aquatic use, I would absolutely pass on any that are known to have been sprayed with any insecticides in recent years, or where the leaves are falling onto a chemically treated lawn or polluted asphalt surface, gutter, or something similar ...That's just common sense, right?
As far as tannins in the leaves, these leaves seem to contain quite a good quantity of them, and you will get a good, golden-brown tint with several leaves in a relatively modest-sized aquarium! (notice I carefully avoided telling you "x" per gallon or whatever...? )
Of course, the extent to which they will tint the water depends upon many factors, like how large an aquarium you have, how many leaves you tossed in, and if you are using any chemical filtration media, like activated carbon, etc., which will remove tannins almost as fast as they're released!
Will they lower the pH of your water?
They could, just like many botanicals, IF you are using water with little to no carbonate hardness...Of course, there are many other factors which can affect the impact on pH of these leaves. And, being natural materials, there are no "guarantees" as to exactly how much they can lower pH. You simply have to observe and test.
On the subject of water chemistry and our good friends, the biofilms, the leaves do seem to contain a fair amount of residual sugars which will cause a bacterial bloom on their surfaces. This is especially noticeable, but not limited to the tip of the stem. These will often go away after a week or so, once the bacteria begin consuming the sugars in the leaves. They should be expected. However, many hobbyists who use these leaves never report such a bloom, yet it's something to be aware of when using them, nonetheless.
There are a couple of ways to prepare these leaves for aquarium use.
We recommend that you rinse them well, then steep them in boiling (ore really hot) water for 10 minutes or so prior to use, and/or soak overnight in fresh water, which will help soften them a bit. This "steeping/soaking helps them sink more easily!
Now, occasionally, when we ship to you, these leaves may arrive with some mold or fungus on their surfaces. This is typically because their waxy "cuticle" does a really good job of retaining moisture, and in the confines of the plastic bag, a sort of "greenhouse effect" ensues. We've found that you can continue to use the leaves without any issues if you give them a little wipe down with a damp paper towel before preparing for use as instructed above. If it's really bad, contact us and we will replace/credit as necessary!
And of course, other times, they'll be rather "dry and crispy", and can be more-or-less "reconstituted" somewhat during the prep process. Magnolia are a bit of a pain in the ass and somewhat inconsistent, when it comes to their condition after shipping. A lot of it depends upon how they are when we receive them here. This can be frustrating..However, for the most part, they are good to use after the prep.
All the good juicy semi-scientific pondering and shipping/prep caveats aside, I can tell you from personal experience that these are awesome leaves to use in our litter beds! Enter the idea of "generic tropical" once again! Yeah, once they're down for a week or two, they have that "look" which makes them great "stand ins" for almost any tropical leaf.
They are safe (if used with the aforementioned caveats), attractive, colorful, and long-lasting. I hope we have cut through some of the fear, clutter, and confusion that's been propagating out there online about utilizing these awesome leaves in our aquascapes!
Magnolia provides an amazing contrast to the other leaves that we use in our botanical-influenced aquariums. Although, admittedly, they're not even in my personal "top 3" in terms of being favorites, they are useful, attractive, and interesting leaves that will no doubt continue to have a place in the hobby, if prepared properly and used thoughtfully.
Stay creative. Stay diligent. Stay observant. Stay thoughtful...
And Stay Wet.