As more and more hobbyists are getting into the idea of using leaves and botanicals in their aquariums, we receive more and more inquiries about what leaves are useable, and how to collect and prepare them for aquarium use. This is a very interesting and fun topic. Although I've spent a lot of time studying and experimenting with various leaves in the aquarium, I am not a botanist, and am certainly no expert on every facet of using leaves you collect in your aquarium. However, the benefits of humic substances, tannins, and other compounds imparted to water by a variety of dried leaves is increasingly well documented and studied, so the growing interest in this subject is quite logical.
First off, a lot of you are probably thinking I'm crazy anyways for encouraging hobbyists to collect and prepare their own leaves. I mean, they're one of the key products that I sell. I'm flattered at the thought that some might think that I am the gatekeeper for "magic knowledge" about leaves and how to use them, but the reality is that hobbyists have been utilizing leaves for decades before I ever even considered the idea. I'm just a bit louder and perhaps more obsessed about it than others! I am also very careful to source my leaves from people who know exactly what they're doing, and who understand our end purpose. And no, my botanical empire will not fall apart if I share some information on collecting and using some of your own leaves in your aquariums!
The first question I usually receive is "Can I use ____ leaves in my aquarium?" Obviously, the most important consideration. The short answer is, "I can't tell you for sure!" The reality is, many, many, many leaves, if used dried and properly prepared, can work in aquariums. Sure, their might be some that have "native" toxic exudates or contain substances that can have deleterious effects on fishes and aquatic life in closed systems. We offer leaves and botanicals which we have determined, through a variety of means- are suitable for our purposes. It's not an easy task, and not everyone would be into it- but it is the responsible thing to do.
Unfortunately, to determine the suitability of the leaves you're considering, you will simply have to experiment with live fishes- not something everyone wants to do, but in reality the only real way to determine wether or not the leaves you're playing with are problematic. You can certainly make use of Google, Wikipedia, and other online botany sites- or even the local college library- to determine if there are known chemical toxins in the leaves you're considering. Tip: Oak, Beech, and other deciduous leaves have been used by hobbyists for some time, and would be good ones to use in a DIY-type situation. You may need to consult someone with a botany and/or chemistry background as well. I spent a lot of time reaching out to various individuals with this information, and it was time well spent. In the end, it was up to me to experiment and put fishes "in harms way" to determine if various leaves were suitable.
The first "generic tip" about collecting leaves with consideration for aquarium use (once you've determined if they are safe for fishes) is to use leaves that have naturally fallen and dried up. These leaves are dead, and have been depleted of much of their natural sugars and other living matter than can essentially become "pollutants" or "boiled" as the leaves die in the aquarium water. You don't want to overwhelm your aquarium with lots of organics caused by using non-dried leaves. A hugely important step. Autumn is, of course, a perfect time to collect leaves for your aquarium!
And of course, make sure that you are collecting the leaves from areas known to be free of pesticides, fertilizers, and pollutants (like factory soot, ash, industrial smoke dust, heavy smog, etc.). This goes without saying; however, it is an important consideration and will eliminate some locations for collection right away. It's really important! When you collect these leaves, make sure that they are naturally fallen, preferably on dirt or grass, as opposed to asphalt roadways and such.
To prepare the leaves, you'd probably first want to inspect them, to make sure that they are free of things like spiders, insects, and other debris that you don't want in your tank. I like to literally give mien a rub down with a moist paper towel, to get some of the surface dust and dirt off of them! Yes, this is time-consuming, but this is the best way to do it, IMHO. You will almost never hear me recommending to just "pick, dump, and pay" leaves into your aquarium. If you've decided to go the DIY route- do it right! Then, I'd give the leaves a day to sort of "air out" a bit in a cool, dark space (like a closet).
From here, the procedures are similar to what we recommend for preparing the leaves and botanicals that we sell here at Tannin. I am a huge fan of an overnight soak in fresh water. You can start with some boiled water, and let the leaves "steep" overnight as it cools. The warm water will further help sterilize the leaves somewhat. Now, a lot of people will tell you that you shouldn't boil the leaves, because it will "crack off" most of the beneficial tannin and humic substances in the leaves, and I'm inclined to agree to some extent. Boiling them is a bit excessive. However, steeping them in boiling water and letting it cool overnight is not, IMHO. Have you ever boiled leaves and then placed them into a container of clean water overnight? Yeah, it will be brown by the next day in most cases, so I don't buy the whole "Don't soak your leaves" mindset. It's a step I almost never skip.
How many leaves to use is a subject we've discussed numerous time here in "The Tint", so I won't really go into it in depth in this brief piece. The bottom line is that you should use caution, particularly when using leaves you haven't tried before. Softer, already acidic water will be more significantly impacted by the tannins and humic substances released by the leaves, driving the pH down more significantly and quickly than in harder, more alkaline water. Color of the water is no guide to how acidic it is. You simply need to test. A pH meter makes this a very simple task. My advice is always to go slowly. There is no need to rush. Every aquarium is different in how it reacts to "inputs" such as the compounds released by leaves, so there is no real "generic answer" that is 100% reliable. "Test and tweak" is the mantra of the DIY leaf-user!
So, in summary- yes- you can and should collect your own leaves if you're up to the task of being responsible and inquisitive. It's certainly fun, and can save you some money (which I expect your'll spend on our tropical botanicals that you can't simply collect in your yard, typically, lol)! However, if you are not willing to take the time to source, identify, prepare, and test, you may want to simply purchase your leaves from a reliable source...like Tannin Aquatics, for example!
So, the leaf vendor is saying it's cool to collect your own..if you're into it.
Stay excited. Stay inquisitive. Stay creative. Stay responsible.
Ans Stay Wet.