BBA Gone: How I Finally Beat Black Beard Algae (Spot Dose Guide)

My exact spot-dosing routine, lighting & flow fixes, and sump refugium tweaks that finally beat BBA—safely.

By FishKeepingLifeCo | Part of the Life in Balance Ecosystem at TheTankGuide.com — Oct 2025

I’ve had Black Beard Algae for years. Back when this tank was a 20-long, it was my sandbox. I ran air stones, sponge filters, hacked HOBs with cut-to-fit sponges, went blackwater, chased reds—you name it. I wasn’t reckless; I knew how to keep fish happy at a minimum. The fun was bending the rules and seeing what else was possible.

I used to follow the “let the tank do its thing” philosophy—no chemicals. Later I warmed up to startup helpers like Seachem Stability, and that shifted my thinking. One habit that didn’t help: the tank sat by the living room TV, so the lights were often on with no timer. Today the light runs a proper plant-first spectrum (no extra white spikes) on a schedule. I’m on a Finnex 24/7 with a custom program.

Before photo of planted aquarium with heavy Black Beard Algae growth — Before: heavy BBA on hardscape and leaves.

Why I Stopped Tolerating Black Beard Algae

When I upgraded to a 29-gallon with a sump, I wanted a clean top—no gear hanging off the rim. It looked great… except the Black Beard Algae kept coming back. People call BBA a lifetime algae. I used to justify it as “still a plant, still photosynthesizing.” What I missed: it was robbing nutrients and light from the plants I actually wanted.

Inconsistent lighting (no timer back then) and the wrong spectrum
Plant melt left in the tank—dying tissue leaks compounds BBA loves
Uneven flow—dead spots let BBA settle and hold ground
Fertilizer timing vs. uptake—when growth stalls, nutrients linger

My Experiments: Why Liquid Carbon Dosing Didn’t Work

I’d tried Seachem Excel before and didn’t love it because I used it like “liquid CO₂.” It isn’t. Used correctly as a targeted algaecide, it’s a different story.

The Game Changer: How to Spot Dose Seachem Excel for BBA

Step-by-Step: The Still Water Technique

Turn off the flow — pumps and air off for about 10–15 minutes.
Load the pipette — around 2ml of Seachem Excel.
Spot dose — aim right at the BBA patch until it lightly clouds over.
(Optional) — one capful over the surface (especially during water changes).
Wait 10–15 minutes — then restore flow.

Aquarist spot applying Seachem Excel with a pipette to Black Beard Algae — During: spot-dosing Seachem Excel with a pipette as BBA enters the red transition phase.

What you’ll see: by day 2–3 that patch turns deep red, then shrivels and lets go. You’ll need to clean intakes/screens for a bit because dead BBA breaks loose—small price for visible progress.

Amano shrimp eating softened red BBA after Excel treatment — Amano shrimp move in once BBA softens and turns red — they won’t touch it in its tough, black form.

That’s when the Amano shrimp move in. They won’t touch it in its black, coarse form — but once it softens and turns red, they eat it like crazy.

Safety notes
Excel can melt sensitive plants if overdone. Go easy with shrimp tanks. Don’t combine heavy Excel and peroxide spot-treatments on the same day. Stay within the manufacturer’s max daily dose when combining spot + water-column dosing.

The Long-Term BBA Fix: Light, Flow, and Nutrients

Fixing those set the stage: I stabilized the light, added a refugium in the sump to eat excess nutrients, and switched to a random flow generator—more coverage, gentler push, fewer stagnant pockets. Then I tackled the algae itself.

Step 1: Fixing the Light Spectrum (No More Extra Whites!)

Keep a real photoperiod (timer) and plant-first spectrum; no “extra white for brightness.”

Step 2: Boosting Flow with a Random Flow Generator

Healthy flow with a random flow generator = fewer footholds.

Step 3: Refugium Power (Starving the Algae)

Refugium = nutrient sink (huge help in the sump).

Prune melt right away—don’t let dying leaves feed BBA.

Seachem Excel bottle in front of an activated sump refugium section — Seachem Excel in front of the sump refugium — the bottle I use for targeted spot-dosing.

Managing My New Problem: Zero Nitrates (The Dosing Life)

Keep nitrates readable (I like 5–15 ppm). My plants now crash nitrates fast, so I test daily and dose accordingly.

TL;DR: My BBA playbook

Fix the environment first: timer + plant spectrum, better flow, remove melt, add refugium.
Spot-dose Excel with pump + air off for 10–15 min; ~2 ml per patch.
Expect red → shrivel → release by day 2–3; clean intakes.
Keep nitrates in range and prune early so BBA has nothing to eat.
Repeat on stragglers; it’s work, but it’s consistently effective.