Keeping yourself "in the dark."

One of the more common questions we tend to receive around here (besides how we became so freaking cool and sexy, of course) is how you can maintain the nice, tinted look to your aquarium water without dropping "mad coin" at Tannin Aquatics every other week!

And yeah, it's a good question!

How far we've come, huh? I mean, it isn't that many years ago that a tank with brown water and decomposing leaves would elicit sympathetic responses and offers to "help you out" of your situation...It's really like a mind set shift in the perception of what's "normal" in an aquarium, and the more and more we see blackwater/brackish botanical-style aquariums popping up, the more "aspirational" they become for a bigger portion of the aquarium hobby.

Okay, maybe "acceptable" is a better descriptor?

I mean, I have to be realistic here. Not everyone is into this decomposing leaves and brown water vibe . Nope.

So, enough of my "state of the hobby" report here...on to the topic at hand.

One of the "keys" to getting your color that lovely brown is to select the right types and quantities of botanical materials to assist. I'll be the very first to raise my hand and call BS on anyone who claims to have a perfect "recipe" for how many Catappa leaves per liter or whatever you must use to achieve a specific color. Yes...there are simply so many variables in the equation- many which we probably haven't even considered yet-that it would be simply guessing.

That being said, there are a few things you can do to help "set the stage" to take maximum advantage of the tint-producing capabilities of your botanicals in your aquarium. One of the easiest is to start out by reducing or eliminating most chemical filtration media, like activated carbon, which excel at removing discoloration from water. Now, I've told you many times that I do use stuff like activated carbon, Poly Filter, or Seachem's ReNew on a more-or-less continuous basis, once I get the color I like in my water.


The other "stage setter" IMHO is to take advantage of the tannin-releasing properties of wood. I know it get's boring hearing me relate to you my sadistic delight about reading those planted aquarium forums and seeing the posts by hobbyists desperate to get rid of the tinted water that their new piece of "high-end" driftwood is producing in their so-called "natural aquarium..."

Tragic for them, but a really good tip for us:

Wood like Mopani, Malaysian Driftwood, and Spider Wood tend to release significant amounts of tannins into the water, particularly when newly introduced, and my attitude is, "Why fight it?" Wood can be your "base tint provider" for your tank for many, many months. In fact, newly-submerged wood can release so much tannins that, depending upon the water volume of the aquarium, you might not need to supplement it with too much in the way of botanicals for the specific purpose of providing "tint" to the water from the outset.

Yeah, simply embracing the readily-aviailable and abundant tannins naturally produced by most aquatic wood is possibly one of the biggest "hacks" in our practice, if there is such a thing!


Of course, you may not be using wood in your tank, or you might be utilizing a piece that you've had for 7 years which has essentially "exhausted" much of the tannins bound up in it's external tissues, so you need to find botanicals which color up the aquarium nicely.

In no particular order, here are my dozen personal favorite botanicals and leaves that are notable for imparting significant color to the aquarium water:

Catappa Bark

Sappanwood Pods

"Ceu Fruta"

Coco Curls

"Rio Fruta"

Alder Cones 

Banana Stem Pieces

Encontro Pods

Magnolia Leaves

Catappa Leaves

Mangrove Leaves

Guava Leaves

And then there are "maintenance materials", like "Fundo Tropical", Birch Cones, "Mini Mariposa", and such, which can be kept out of sight in a filter media bag inside your canister filter or other power filter, or simply left in a media bag the sump or some other innocuous place where they have regular contact with the water, to passively impart color into the tank.

And of course, there are dozens more, and new materials being added to our selection all the time, each with unique characteristics just waiting to be discovered and utilized by hobbyists worldwide!

And a quick general note- you can usually get some indication as to what color and how intense the color a given botanical will impart into your water when you prepare it...That initial burst of tannins and other coloring compounds is immediately obvious and probably quite helpful in determining the color "palette" to expect!

Really, IMHO the top botanical item for consistently and effectively producing "tint" is Catappa Bark. I LOVE this stuff. We have three different varieties- that's how much I love the stuff! (I see botanicals as others see coffee, with many factors creating unique differences in ones from various locales).

No, it isn't the cheapest material out there. It never will be. We're bringing in a lot more of the stuff to help lower the price a bit, but it's simply never going to be "cheap." It requires more labor on the part of the people who harvest and prepare it, and they have to manage the resource carefully to avoid damaging their trees by taking too much, too fast. 

That being said, scientific research indicates that Catappa Bark seems to have a very concentrated quantity of tannins and other compounds bound up in its tissues, which means you don't need to use a ton of the stuff in most aquariums to enjoy the benefits of its capabilities. I personally feel that it "lasts" a long time (several weeks, at least) in terms of imparting color into the water. And it looks cool. Yes, it actually has an incredible aesthetic that makes it even more attractive from multiple standpoints. 

We talked recently about botanical "layering", and I still recommend that progression as the way to "stock" your blackwater/brackish, botanical-style aquarium. It also give you the opportunity to evaluate your scape and the impact of the materials you're using at each and every step along the way.

Since we really can't effectively "test" for tannins in a way that is meaningful/helpful/relevant to our practice just yet (there ARE tannin test kits, BTW, but interpreting the results in our context needs work), we tend to focus on the visuals, and having a sort of process like "layering" gives you that opportunity to evaluate with the means that we have at our disposal at this time. 

In terms of longevity of materials, we've long advised that (no surprise here) most of the more "woody', dense materials will last a lot longer than the more "ephemeral" ones like leaves and softer, thinner seed pods and such. Some of these, by virtue of their hard dermal layer, like "Jungle Pods" and "Savu Pods", tend to not impart a lot of visual color into the water, but last a very long time. Others, like "Monkey Pots", last a long time, and tend to leach out more material via their outer layer of tissues for longer periods.

Replacement of botanicals, as we've pointed out many times, is largely a subjective thing, and the timing, frequency, and extent to which materials are removed or replaced is dependent upon multiple factors, ranging from base water chemistry to temperature, to the types of aquatic life you keep in the tank (ie; xylophones like certain Plecos will degrade botanicals more quickly than in a tank full of characins and such).

It's never a bad idea to keep an extra supply of some of these "tint producers" on hand...

The other practice that can help you maintain the tint, as we've touched on many times, is to steep some botanicals or leaves in your makeup water, thus ensuring ga "base level" of color at all times, topped of when you do your regular water exchanges...

Many of the less durable botanicals will last several months, at least "structurally", but might be far more limited in terms of their  impartation of color to the water- perhaps a few weeks in many cases.

This is the part of our hobby that is as much an "art" as it is a "science". 

Monitoring pH, visual tint, nitrate and phosphate are but a few of the things you should undertake as part of the active management of a blackwater aquarium. To me, that's a huge part of the fun. We offer general guidelines and "best practices", but really, each tank is a "one off", and more customized approaches are the way to go. Again, this is what makes our little sector of the hobby so compelling, IMHO.

So the real key to "keeping yourself in the dark" with botanicals, is to experiment and observe. Since there is no real "plug-and-play" aspect to natural, botanical-style, blackwater/brackish aquariums.

It's all about doing.

Get out there and do! And enjoy.

Tint the world.

Stay creative. Stay innovative. Stay curious. Stay bold...

And Stay Wet.


Scott Fellman

Tannin Aquatics







Scott Fellman
Scott Fellman


8 Responses

Peter Ashby
Peter Ashby

August 25, 2018

I have three alder cones in my filter, in with the ceramic beads and before the fine filter/chemical media basket (just phosguard at the moment). Though something in the tank/filter seems to be soaking up the tannins and its the nice ‘strong black tea’ from alder cones in the change water bucket over a week which is doing the business. A noticeable darkening on this morning’s 20% water change. If you put the peat before the fine filter I can’t really see the problem.

I’m wondering if my humate sub soil is soaking up the tannins? I had to boil the bogwood arch just to get it to sink but I only boiled it long enough for that. Should have kept the water and concentrated it down as blackwater extract. Could be that piece of wood is absorbing instead of giving out. I’d be surprised if the plants are absorbing it, but stranger things have happened.

Good job the alder trees had some old cones from last winter left, they’ve been very good. There’s a good crop of new ones developing. The trees are by the local burn, down in a cleft. The countryside here is dodgy as it’s all agrarian and you can’t know what has been sprayed in the vicinity. The water in the burn is nicely dark, it will have filtered through some peat up in the hills, not a lot but some. All the Scottish rivers hereabouts are tea dark from peat. You get foam on top as well, looks ‘chemical’ but is entirely natural. Good trout and salmon rivers.

Peter Ashby
Peter Ashby

August 25, 2018

Further to my point about phalaenopsis orchid leaves. I’ve recently put ‘fresh’ ones in as the old ones have broken down and I’ve just seen one of my pearl gouramis eat part of one. They do this to any mulberry leaves I put in is a first for the phals. This might be because the first phal leaves happened to fall towards the back of the tank while a couple of pieces this time are at the front.

That fish, from an area where this orchid grows naturally, are eating dried leaves in the water pretty much confirms that my decision to introduce them is a good thing.

So if one of the phals someone has given you dries out a terminal leaf consider taking it for your tank. Especially if you have gouramis.

Scott Fellamn
Scott Fellamn

August 01, 2018

Hi Peter,

Excellent write up and cool experiences! Interesting to hear of your experience with Mulberry leaves! We offer them more as a food for shrimp people…but I can’t imagine why they wouldn’t have at least some value as an “environmental enhancer”, too. Obviously, as your finding, shrimp aren’t the only animals which seem to have a taste for them!

Please keep me updated, and thanks for your feedback!



Peter Ashby
Peter Ashby

July 29, 2018

I’ve very recently (just less than 2 weeks ago) converted our soft water, slightly acid 10gallon tank from an undergravel filter for an external canister and took the opportunity to add some more bogwood to replace that the ancistrus cats have eaten (half the large arch which used to span most of the tank) and get some leaves in and some alder cones. I decided putting two in the change water was sensible before I read your recommendation.

The leaves included green dried mulberry leaves and much to my surprise the newly added lace gouramis have been eating them. I added a replacement leaf 3 days ago and it is almost all gone now. I suspect the ancistrus has had a go as well but the gouramis was a surprise.

Also because I have some on hand as an orchid grower and because they hail from across Asia and my tank (ancistrus apart) is meant to be a mid Malayan peninsula biotope I added two dried phalaenopsis orchid leaves and have noticed the fish browsing off them and haven’t lost anyone or measured a problem.

Can’t pin it specifically but my Anabastia sidthimunki’s have become very secretive of late retiring to under the large flat base of the half arch, too small for the ancistrus. Prior to this one of them, the male I suspect turned a golden background colour while ungolden female got fat, I would say gravid. I’ve been putting microworms and liquifry in the tank just in case. The gouramis dig the microworms too, picking them from midwater. So fingers crossed.

I have a track record of sort in the previous incarnation of the tank having accidentally induced kuhli loaches to spawn and the current ancistrus was born in the tank. When I netted him for the transformation he was so traumatised he latched onto the net and was very reluctant to let go. Never been netted before. He is less secretive in the new tank with more hiding places and screening plants. So success in that area. But it makes the secretiveness of the loaches all the more intriguing.

I’m definitely sold on the blackwater leaf aquarium and can’t wait for autumn when I can collect some local leaves. I may have to buy some more mulberry leaves though . . .

Scott Fellman
Scott Fellman

July 26, 2018

Yes, Rooibos is used here in the States as well; it’s a really good “hack” too! And hey, it drinks well, which is more than I can say about the peat pellet-infused water we make…lol



July 25, 2018

You can also add tint to your water with tea. Here in South Africa rooibos (red bush) tea is popular for fish tanks. The normal fermented tea gives the water a reddish tint but if you use green rooibos the tint is more neutral.

I haven’t tried other kinds of tea but I’m sure it would also work. I just float a teabag in the aquarium until I like the colour of the water. One teabag for 100l of water works for me. Very cheap way of getting tint.

Scott Fellman
Scott Fellman

July 25, 2018

Hi Michael,

Peat pellets are just fine; hobbyists have used peat for years and years with greta results. We just haven
t offered peat because the sourcing was a little tough- in terms of sustainability and such…and the perception among the public that it wasn’t. Sustainable peat production for horticultural uses is now taking place in Canada, so that might change. Peat is great for the purpose you’re considering.




July 25, 2018

Hi, I wanted to ask you about the use of peat pellets in my filter. Is this a good way to keep my water tinted? Or is this a bad idea? Kind Regards

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