Tannins: The Pros & Cons of Blackwater for Beginners

Everything you need to know about the impact of tannins in your freshwater ecosystem in one complete and beginner friendly video. We are covering the how, what, and why’s of blackwater and tannic aquariums, the pros and cons of their use, as well as where to source your botanicals from properly. We will also teach you exactly how to add them or remove them from your aquarium- fast!

Tannins in Aquariums FAQs

Q: What are tannins?
A: Tannins are natural compounds released by leaves, seed pods, and wood when they break down in water. They give the water a golden to brown color, similar to black tea.

Q: Does brown water mean my tank is dirty?
A: No! Brown water from tannins is not dirt. True black water is defined by soft, acidic chemistry with lots of dissolved organic matter—not just color.

Q: How do tannins affect water chemistry?
A: Tannins lower pH and soften the water. This helps keep nutrients like iron and manganese soluble for plants and creates conditions many fish prefer.

Q: What are the benefits of tannins?
A:

• Reduce fish stress by mimicking natural habitats

• Improve breeding for species like tetras, bettas, and dwarf cichlids

• Bind harmful trace minerals

• Offer antimicrobial and antifungal protection

• Help suppress algae and harmful pathogens

Q: Are there myths about tannins I should know?
A: Yes! Brown water does not equal dirty water, and clear water does not equal healthy water. Stability and appropriate chemistry matter more than clarity.

Q: Which fish benefit most from tannins?
A: Fish that naturally live in blackwater habitats—tetras, bettas, and dwarf cichlids—thrive in tannin-rich conditions.

Q: Is adding tannins just a personal preference?
A: Yes. Some hobbyists prefer clear water, others love the amber tint. Both are fine as long as the fish are healthy.

Q: How can I add tannins to my tank?
A: Common sources include driftwood, leaves, and seed pods, which slowly release tannins over time.

Q: Do tannins affect algae growth?
A: Yes! By reducing light penetration and lowering pH, tannins help limit algae growth in the tank.

Q: Can I remove tannins if I want clear water?
A: Yes. Regular water changes will gradually clear the water. For faster results, filter media like Seachem Purigen can remove tannins, odors, and organic wastes quickly.