One of the cool things I've noticed in our office tank lately is the unusual and unpredictable rate at which leaves will break down and decompose. It's weird; seems like some months, the leaves will break down very quickly, after just two weeks or so...Other times, we'll see leaves hang on for a long time- a month or even more. Magnolia and the larger Catappa leaves are particularly notable for this.
I've had one Magnolia leaf that's fairly prominent in my display (the larger one in the center of the wood) hang on for well over a month now...
I've noticed that some of the larger Catappa leaves (particularly the Sandaken, Borneo variety) seem to hang on longer than others. This is nice, because it is one less thing to think about during routine maintenance routines.
And Guava...let's talk about Guava leaves for a second...Simply stated, they last a good long time. They really don't break down nearly as quickly as the Catappa leaves, and hold shape nicely. They might look a bit more "gnarly" or maybe a bit "rough" when you receive them; however, one submerged, they "deploy" nicely and hold up for a long period of time...sometimes 2 or more months- before breaking down! This durability, coupled with their "exotic" look is what I really enjoy about them.
And then we have Jackfruit leaves...
They're sort of the "forgotten stepchild" of the aquatic leaf world...not super popular, but possessing a cool look and quiet, but significant ability to tint that no one really talks about (okay, we do).
And did we remember to tell you that they're durable? Yeah, they last a good long time...like a month or more in our experience. They do recruit biofilms fairly quickly, much in the way Magnolia leaves do, and you can easily remove the film if it gets too gross for you (i.e.; if it insults your "aesthetic sensibilities..!").
With almost any leaves, I'm pretty sure that there are factors which contribute to their longevity and durability in our aquaria, ranging from how dry the leaves were when submerged, the time of year, conditions under which the leaves were prepared...and of course, water parameters...
It's the same in nature, I'm sure...leaves decompose at rates that are dependent upon many environmental factors.
(Rio Negro "leaf porn" by Mike Tucc)
My hope is that we eventually are able to make solid determinations about how leaves behave underwater, and what conditions should be utilized for their collection, preparation, storage, and utilization in order to extract maximum benefits (in therms of both tannins and durability) from them.
Until then, those of us who play with leaves...and other botanicals, for that matter- in our aquariums- will continue to be on the 'bleeding edge" of technique for this stuff...That means that each and every one of us who uses these wonderful natural offerings can make meaningful and important observations and contributions to the state of the art in this cool hobby niche!
Stay observant. Stay engaged. Stay collaborative.
And Stay Wet!