One of the discussions I have a lot with customers is, "How many___________ do I need for my _____ gallon tank?"
And that is a great question, because the best answer is, "It depends."
Yeah, not a particularly helpful answer, huh?
Seriously, there are a ton of variables involved in figuring out how many of a given botanical you need. And I think it starts with asking yourself a series of questions. Most important, you need to look at just what you're trying to achieve.
In other words, if your goal is to mimic an Amazonian stream bed, replete with lots of leaves, seed pods, and other botanical debris, you probably want a fair amount of "coverage" on the bottom, so depending on the size of your aquarium, you may want to utilize several of each of the botanicals you have in mind. If you're just looking to add a few random "Savu Pods" or "Jungle Pods" to your tank to act as a shelter or breeding location, then 2-4 specimens should do the trick.
Use our "variety packs" for a sort of "botanical stocking density" guideline. For example, if you're looking at replicating a Morichal environment, for example, you could look to our "Vibrante Morichal" pack for some guidance. We developed this pack with enough materials in when we felt are good densities and ratios to create a reasonably effective representation of this environment in up to a 50 US gallon tank. Obviously, if you're working with a smaller tank, there will be a higher density of botanicals in there. On the other hand, if you like a LOT of stuff, you may want to add more than one pack (over time, of course). There are no real "rules" about this stuff, aesthetics-wise!
The usual considerations need to be addressed, like the need to add materials slowly to ANY aquarium which has fishes, and ONLY after you have taken the time to properly prepare these materials for aquatic use. The amount of potential tannins and other organics deposited into the water by adding a large quantity of botanicals all at once in a populated, established aquarium could prove devastating to its inhabitants, so you simply cannot rush this process. Go slowly.
Doom and gloom aside, the aesthetic considerations will typically influence most hobbyists' "botanical stocking density."
Leaf litter beds are a bit easier. Well, you have to do some "fish geek math" to estimate how many of a given number of say, Medium Catappa or Guava leaves you might require to do what you're trying to do. If you want a fully-covered substrate with lots and lots of leaves, you probably are looking at a fair number of leaves- perhaps two dozen or more in a 40 US gallon "breeder) aquarium, with dimensions of 36'x18"x 17" (91.44cm x 45.72cm x 43.18cm). If you just want to have a smattering of leaves in the tank here or there, anywhere from 6 to 12 leaves should be enough to start with. You can always "edit" and add more as desired to achieve the effect you want.
And if you should "over-do it" and end up getting more leaves than you need? Well, you can always end up having some extras for replenishment as the leaves break down. See, nothing is ever wasted in a botanical system!
And of course, there are other considerations, such as the amount of "tint" you're trying to achieve. Obviously, you're not going to want to load your aquarium to the rim with Catappa leaves unless you really like the brown water, right? Well, as we've discussed before, you could simply use a lot of activated carbon in your filter to create "white water" conditions in your aquarium. even when stocked heavily with leaves and such. If you recall, I endured this painful scenario several months back with my office tank, to make this point!
Obviously, any pice on "how many pods to use" in your aquarium is purely speculative. Your needs, desires, tastes, expectations, and comfort levels will be far different than mine, or any other hobbyist's. In the end, it's all about what works for YOU.
Our best advice with botanicals: Purchase more than you need to start with, but start with less than you need.
Yeah. Slow and steady. Simple.
Stay disciplined. Stay enthusiastic. Stay curious.
And Stay Wet.