Blackwater botanical method aquarium with community fish by Betta Botanicals.
A blackwater botanical method aquarium with community fish.

Blackwater and Botanical Style Aquariums are Different

One of the dividing rifts between hobbyists that utilize botanicals in an aquarium is whether you have created a Blackwater Aquarium or a Botanical Style/Method Aquarium. They have many similarities (botanicals, tinted water, replication of nature), but their chemical composition is what sets them apart. 

Blackwater botanical paludarium for betta fish by Betta Botanicals.
Blackwater botanical paludarium.

What is the Chemical Composition of Blackwater?

The major difference between a Blackwater, Whitewater and Clearwater body of water are the  concentrations of sodiummagnesiumcalcium, and potassium; these are very low in black waters. Hobbyists replicating this environment often will use an RO or RODI unit. These units will remove almost all the ionic compounds dissolved in the tap water, leaving water that can be influenced by the acids and nutrients released by the organic acids in aquarium botanicals. As we know, botanicals release varying amounts of humic and tannic acids, so their use with RO water often drops the pH below neutral. The golden number I hear Blackwater enthusiasts try to hit is 5.4 (remember that 7.0 is neutral).

Biofilms in a blackwater aquarium with aquarium botanicals by Betta Botanicals.
Biofilms in a botanical method aquarium. 

What is Blackwater?

Blackwater habitats have low ionic concentrations of Sodium, Magnesium, Calcium and Potassium. Their pH's are very acidic, often between 3.6-5.4. They have dark, tannin-stained water and the conductivity of the water is quite low (like pure rainwater). These habitats also favor animals who don't calcify their shells, think snails and plankton! Most often they are connected to forest basins with sandy substrates. This 'tea-stained-water' is achieved in areas where the rates of organic inputs into the river are higher than the ability for the ecosystem to break them down into the final stage of release, as CO2. ...kinda like my laundry basket. No matter how much I do my laundry, there is always something I missed! HA! They contain barely understood communities of organisms, very low levels of bacteria and the aquatic vegetation is adapted to low light conditions.  

A Botanical Style Aquarium for Betta Hendra with salvinia cucullata, southern live oak, and a nutrient rich substrate.

What is a Botanical Style Aquarium?

Simply put. We understand it to be an ecosystem approach to aquarium keeping. 

Not so simply put; it's a way of creating a more complete environment for our fishes that can't be bound by a scientific definition of what the water chemistry, color or plant composition has to be. We don't chase a pH number. Sometimes the water is tinted and sometimes (either through carbon or water exchanges) the water is not tinted. We use plants, or sometimes we don't! Sometimes the botanicals match the location the fish come from, and sometimes they don't! 

A botanical style aquarium for domestic bettas utilizing catappa leaves, catappa bark, and oak leaves.

What are the similarities between the two?

Botanical Style Aquariums and Blackwater Aquariums utilize many of the same materials to create an ecosystem. The use of botanicals is an obvious one. But the nuances of how they are used is similar, beginning with a few materials, adding more over time, embracing the biofilms, the detritus, and letting the system balance out. We don't go around scrubbing every surface for algae (usually just the front glass panel), but some scrub all the glass walls for an aesthetic appeal, and we are okay with that! Every week or so we do a small water exchange, move this, tweak that, but we never gravel vac the substrate because we know there is life in it that helps to keep the system balanced. We still feed the fish once or twice a day, but we know if we skip a feeding there will be supplemental food sources the fish can forage on. It's a beautiful thing to achieve in the aquarium, and it all begins with rethinking what a normal aquarium should look like.

If you create a tank with rainbow gravel and botanicals, please send me a photo because I want to see that!

Let me know what you think below! Has the use of botanicals changed the pH of your water in ways you weren't expecting? For me, the water only drops in pH a little because I use tap water in all my tanks.

Let's chat again soon! Happy scaping!



  • Brenda: December 04, 2021
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    One time I put too much almond leaf powder that I got from Bay Area bettas and it caused a rapid drop in ph (over a few days) and crashed my cycle. I wont do that again, leaves from now on!

  • Dylan Renke: November 03, 2021
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    I like the distinction between the source water of the Blackwater aquarium versus the botanical style aquarium. Blackwater can almost be like a desert of sorts, relying on outside input to create an environment suitable for life.

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