As huge proponents of employing aquatic botanicals (or what one of my reef keeping friends like to call "twigs and nuts") in the aquarium, we've learned quite a few things about them. We've become surprisingly experimental, and very keen on pushing the limits in aquascaping. As a result, we've been able to determine some characteristics and "behaviors" associated with their use as dynamic hardscape materials. We may sounds like a broken record at times, but you -our customers and fans- want to know the ins and outs of this stuff, and we're happy to oblige! Here are some thoughts based on our use of these materials in aquariums:
1) Aquatic botanicals are not "forever" aquascaping materials. They will soften, break down, and otherwise decompose over time. Some, like leaves, particularly Catappa and Guava, will break down more rapidly than others, and if you like the look of intact levels versus partially decomposed ones, you'll want to replace them more frequently; typically on the order of every three weeks or so, in order to have more-or-less "intact" leaves in your tank. On the other hand, if you like the more natural look that occurs as the leaves break down, keep 'em in. You may need to remove some materials if you find fungal growth or other "nastiness" (yeah, I'm using that terms) that you feel is unsightly, smells bad, or is otherwise untenable.
Botanicals like the really hard seed pods ("Savu Pods", "Jungle Pods", "Terra Sorrindno", etc., can last for many, many months, and generally will soften on their interiors long before any decomposition occurs on the exterior "shell" of he botanical. Often times, fishes like Plecos, Otocinculus catfish, and other bottom-dwellers, will rasp or pick at the decomposing materials, further speeding up the process. Others, like ornamental shrimp, Apistos, and others, will pick at biofilms covering the interior and exterior of various botanicals, as well as at the microfauna which live among them, just as in nature.
2) As botanicals break down, you will see an almost immediate impact on the color of the water. It will typically be clear, but with a tannish or brownish tint. The degree of tint will be determined by various factors, such as how much of the materials you use in your tank, how long they were boiled and soaked during the preparation process, and how much water movement is in your system. Unfortunately, since these are natural materials, there is no set "X pods per ___ gallons of aquarium capacity", and you'll have to use your judgement as to how much is too much!
3) If you really dislike the "tint", but love the look of the botanicals, you can mitigate some of this by employing a longer "post-boil" soaking period- like over a week. Keep changing the water in your soaking container daily, which will help eliminate some of the accumulating organics, as well as to help you to determine the length of time that you need to keep soaking the botanicals to minimize the tint. Of course, you can always employ chemical filtration media, such as activated carbon, and/or synthetic adsorbents like Seachem Purigen to help eliminate a good portion of the excess discoloration within the preparation bucket and/or the display aquarium where the botanicals will ultimately "reside."
4) You'll notice over time that many of the aquatic botanicals will "redistribute" throughout the aquarium, being moved around by both current and the activities of fishes, as well as during our maintenance activities, etc. This is, not surprisingly, very similar to what occurs in nature, where various events carry materials like seed pods, branches, leaves, etc. to various locales within a given body of water. In our opinion, this movement of materials, along with the natural and "assisted" decomposition that occurs, will contribute to a surprisingly dynamic environment.
5) Just like in nature, if new botanicals are added into the aquarium as others break down, you'll have continuous influx of materials to help provide enrichment to the aquarium environment. As hinted above, this type of "renewal" creates a very dynamic, ever-changing physical environment, while helping keep chemical changes to a minimum. The fishes in your system may ultimately display many interesting behaviors, such as foraging activities, territorial defense, and even spawning, as a result of this regular influx of "fresh" aquatic botanicals. You could even get pretty creative, and attempt to replicate seasonal "wet" and "dry" times by adding new materials at specified times throughout the year...The possibilities here are as diverse and interesting as the range of materials that we have to play with!
The whole idea of using aquatic botanicals in aquariums is not entirely new, as it has long been known that these natural materials provide various chemical benefits to the aquarium inhabitants. However, the idea that these are also great for creating unique aesthetics and physical experiences, and the regular availability of quality materials with which to experiment- is something that we've come to appreciate as a new way of aquarium thinking. With more and more hobbyists playing with botanicals and experimenting with aquascaping concepts employing them as a part of the hardscape, we're excited to see what kinds of creative ideas arise out of the "new botanical" movement!
We look forward to seeing what you come up with! Embrace "the tint!"
Stay creative. Stay motivated.
And stay wet!