Keeping your tank in the dark...literally!

Are you into the tinted look of blackwater, but you're not totally sold on the idea of a pile of leaves and seed pods and stuff in your tank?

Totally understandable. I can think of dozens of reasons why you might love the tint but not like the botanicals in your aquarium, and we do receive a fair number of inquiries about the best ways to get the "tint" into your tank are without having to keep all of those leaves and such in the display.

Fortunately, it's almost shockingly easy. You simply prepare the makeup water that you use for water changes with some botanicals to help influence the water tint and pH. No brainer, right? Well, there's a bit more to it than that, but that's sort of the basic idea...

What's the most efficient way? Well, it depends. If you are looking to lower the pH significantly in your aquarium, you're advised to start off with water that has little to no alkalinity (like reverse osmosis/deionized water), and start from there. You'll want to reconstitute it somewhat to retain some buffering capacity in many cases, and there is a lot of information out there on the internet by people with chemistry backgrounds that can explain this way better than I can. Avail yourself to it.  As we've touched on previously, there are a lot of ideas out there about how to handle the "dance" that is alkalinity and pH in our water, and we'll sort of spare the gory details for the sake of keeping this piece simple and on point today.

Like many of you, I store my water in plastic containers for use during water changes. Over the years, I've sort of worked out a rough "formula", if you will, to create consistent "tint" and conditions for my makeup water. Typically, I'll add 3 medium-sized Catappa leaves to a 5 gallon container of "straight-up" RO/DI water. This has always given me a nice even color and a pH around 6.5-6.6, which is the range I maintain in my display aquariums.

Botanicals will gradually break down and impart tannins, humic acids, and other organics to the water which may affect pH; just how pronounced the effect is in your aquarium will depend upon a number of factors, including the starting pH and alkalinity of the water, and the number of botanicals you add to a given volume of water. "Your mileage may vary" as they say, and perhaps a different number of leaves in a different sized container works for you. Obviously there are many variables, even in as simple a practice as steeping leaves in your makeup water, like the source of the leaves and their "potency" (in regard to tannins contained in their tissues), the age and condition of the leaves, temperature, etc., etc., etc.

Because we're asked...a LOT- let's narrow down the botanical field for a second, to some of the particular items that we feel will lend themselves well to imparting tint and lowering pH in your aquarium. 

Alder Cones: These are potent little tannin-producing botanicals, which, in my personal experience, are best suited for "habitat enrichment" rather than their utterly terrestrial, "non-tropical" appearance! You can prep them and place them easily into a filter age passively, or in a canister filter, outside power filter, or cartridge filter. A handful of these little cones can tint a 10 gallon tank quite easily, in my experience. Similar results may be had with the Indian Casuarina Cones and Birch Cones. You'll need to experiment to see what works best for you!

Fundo Tropical: This coco-derived product is great for aesthetics- forming a cool substrate component. However, it's equally adept at providing tannins and humic acids as a "water conditioner" as well! You can use it just like the Alder Cones- in a filter or passively in a mesh bag. To gain maximum benefit of it's tannin-producing qualities, reduce the boiling time to just a few minutes.

Catappa Leaves: The "classic" botanical has been used for many years for just this purpose. Instead of throwing them in the tank, you can easily use them as above, in a  filter or mesh bag, and they'll impart their magic not the water easily and quickly. Again, since you're not worried about them sinking, you could maximize the tannin-release by steeping them in hot water for a few minutes before incorporating into your filter. Oh, and  another super potent "tint aid" is Catappa Bark!

Coco Curls: These are overall awesome botanicals- attractive for aquascaping, but surprisingly useful to help "tint" the water, as well!

Mopani Wood: Yep, it's a bit pricy because of it's relative scarcity in the trade, but this stuff puts out some serious tannins, and depending upon how long you soak it prior to use, it can impart tannins for many, many months. In fact, I've had pieces in smaller tanks (like 20 US gallons), that were soaked minimally, and imparted a beautiful (okay, to ME, anyways) brownish tint for over a year! Oh, yeah- it's some of the most beautiful wood used in the aquarium world, too. 

And of course, I could pretty much go on and on with the whole catalog of stuff we offer; however, these are the best ones, IMHO for doing the "tint" thing!

I'd be remiss if I didn't at least mention the "golden rules" of using botanicals to influence your water chemistry, which we've talked about over and over and OVER here:

1) Always follow our preparation recommendations (boiling and/or extended soaking) prior to adding botanicals to your aquariums for any purpose- be it "aesthetic" or "functional." It's not the most enjoyable thing in the world to boil stuff and then soak it, but it's one of the best ways to a) release some of the organics, dirt, and other impurities that might be bound up in the surfaces of the botanicals, and b) helps to saturate their tissues, softening them and water logging the botanicals so that they sink more readily (something that's more important in specimens destined for display tank, but you get the idea here...).

Aquarists always wonder how much of the tannins they might "lose" through the preparation process, particularly in regards to leaves, and the answer truly is that I don't know for sure. I can tell you that most of these items will continue to release tannins over time as long as they are submerged. I suspect that the amount of tannins lost as a result of proper preparation is far less than the potential risk you expose your aquatic animals to when you don't prepare them for use. That's MY opinion, of course.


 2) Always GO SLOWLY and add botanical-influenced water, or botanicals themselves to your established aquariums gradually. Because you have a stable system, and are adding materials that can impact the water chemistry, and indeed, add to the bioload or affect water quality to some extent, it's really important to gradually add the botanicals to your system. This will give you the opportunity to gauge for yourself the impact on your water parameters that the materials impart, and to allow your fishes, biological filtration, and aesthetics to adjust to the changes. Remember, fishes don't always react well to (rapid) environmental changes. Err on the side of caution and go really slowly. What's the rush, anyways?

One of the things we've touched on before, which deserves repeating is that there is a difference between the the "tint" that you can often expect botanical materials (leaves, wood, seed pods, etc.) to impart to the water and an impact on pH and alkalinity.  Just because the water is brown doesn't mean that you have "Orinoco-like" conditions in your tank! In many cases, botanicals will have almost no influence whatsoever on the alkalinity. However, depending on the alkalinity and other environmental factors, they can affect the pH...To what extent is hard to predict. Water with minimal to no general hardness can be influenced way more significantly with botanicals, and if you're not careful, you can create a downward spiral of plummeting pH and it's associated problems. A little research, patience, and care goes a long way towards preventing any problems in this area.

The overall approach to observing what influence botanicals can have on your water chemistry is sort of a no-brainer, right? You simply have to add the botanicals and monitor your basic water parameters after you add them to compare them to your results prior to adding the botanicals.

Maybe it's the overly-cautious reefer in me...or just the cautious way I was trained in my formative hobby years by my father, and experienced hobbyist himself, but I think that it's just common sense to follow the directions we prescribe for preparation, and to use a healthy dose of good old-fashioned patience- coupled with common sense- when using these items in your aquatic displays. Observe your animals...Test your water regularly.

As usual, we can go on and on about this stuff, so we'll rap it up here. The point is, you can do many cool things with botanicals, apart from just giving your water that golden-brown color we obsess over here. The extent to which you will go, and the way you'll get there, of course, are based on your own decisions and needs. And you can do it safely and comfortably for both you AND your fishes!

It's actually pretty easy to keep your aquarium "in the dark!"

Stay patient. Stay observant. Stay enthused.

And Stay Wet.

Scott Fellman

Tannin Aquatics



Scott Fellman
Scott Fellman


Leave a comment