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Aquarium Algae: What Will Eat It & How to Treat

Algae is a naturally occurring process in ALL aquariums.  Balancing algae blooms can be frustrating and defeating at times.  So before you throw in the towel on the hobby, let’s take a closer look at common algaes, how they grow and how to defeat them. It’s time to stop scrubbing away algae and start enjoying your beautiful underwater creation.

Common Aquarium Algaes:

A great resource for common algaes and how to combat them is Julian Sprung’s Algae: A Problem Solver Guide. With a focus on common herbivores that combat common algae issues, this book is easy to follow and has PICTURES!!!  It’s a MUST HAVE in any aquarium library.  


Before we dive into the common aquarium algaes, let’s look at a few herbivores that are essential soldiers in the combat of algae.

  1. Copepods and Amphipods
  2. Seahares (link to article) and Snails
  3. Hermit Crabs, Emerald Crabs and Urchins
  4. Tangs, Blennies and Rabbitfish

Other ways to control algae include:

  1. Refugiums
  2. Macro Algaes and Mangroves
  3. Chemical Media: carbon, GFO (granular ferric oxide)
  4. Protein Skimming, UV Sterilizers and Ozone
  5. Medications and Algicides  
  6. Last but not least…Good, old-fashioned elbow grease (manual removal of algae).

As highlighted in Sprung’s book, here are some common algaes

and how to win the battle and the war on algae!


Algae Type: Characteristics/Cause:

Green water, pea soup

(Green Phytoplankton)

Often times referred to as “Pea Soup,” this cloudy, green water can prevent visibility for days or weeks.  This free-floating algae bloom is most commonly caused by:

  • Excessive organic waste build-up
  • High Nitrates
  • Too much light
  • Macro Algae Reproduction

What will eat it?


Ways to Treat it?

  • UV Sterilization
  • Protein Skimming
  • GFO
  • Water Changes using RO Water



Green Hair Algae (GHA) (Derbesia)

Fine filamentous “hair” generally grows in low flow areas and feeds on phosphates and nitrates within the aquarium.

Common Causes:

  • Low-quality carbon
  • Unrinsed, dirty foods
  • Over feeding
  • Tap or Well Water
  • Low flow
  • Direct sunlight exposure
  • Low Alkalinity (below 8 dKH)

What will eat it?

  • Hermit Crabs
  • Trochus, Astrea, Turbo and Cowrie Snails
  • Tuxedo and
  •  Long-Spined Urchin
  • Bristletooth Tangs
    •   (Kole, Chocolate, Chevron)
  • Zebrasoma Tangs
    •   (Yellow, Purple, Sailfin, etc)
  • Arcanthurus Tangs
    •  (Powder Blue, Brown, Goldrim etc)
  • Rabbitfish
  • Lawnmower Blennies

Ways to Treat it?

  • Manual Removal
  • Water Changes
  • Stabilize Alkalinity
  • Increase water flow
  • Refugium
  • Nutrient Reduction By:
  • Rinsing food and controlled feeding
  • Use of RO water
  • GFO
  • Protein Skimming
screen-shot-2016-11-14-at-5-13-20-pmBryopsis Commonly referred to as feather or plumrose algae, Bryopsis is a green or bluish fern-like problematic algae, often confused with common GHA.

Common Causes:

  • Hitchhiker from corals or other liverock added to system
  • Any level of ammonia and nitrite will cause outbreaks if present in the aquarium

What will eat it?

  • Rabbitfish
  • Long Spined Urchin
  • Tuxedo Urchin
  • Emerald Crabs
  • Lettuce Sea Slugs (Elysia sp)

Ways to Treat it?

  • Raising magnesium levels with Kent Tech M
  • Manual removal
  • Strong biological filtration
  • 3% Peroxide dip of rocks, coral skeletons and decor with bryopsis (will kill living corals)

Bubble Algae

(Valonia, Verntricaria  & Dictyospharia)

These spherical or oblong shaped “bubbles” of algae are filled with thousands of new bubble algae.

This algae is commonly introduced as a hitchhiker from corals,  liverock or other decor added to an aquarium from an outside source.  


What will eat it?

  • Surgeonfish/Tangs  (Sailfin, Yellow, Purple, Naso,Hippo tang etc.)
  • Rabbitfish
  • Emerald Crabs

Ways to Treat it?

  • Manual removal
  • Siphon removal
  • Low nitrate levels

screen-shot-2016-11-14-at-5-13-42-pmBrown Hair Algae


Brown hair algae is commonly found in cooler water temperatures, showing up in winter months when aquarium water temperatures can drop.  Much like GHA, this cotton-candy-like algae is generally caused by high nutrients, namely phosphates.

Outbreaks can be caused by use of poor quality carbon, over feeding and poor water circulation, all which contribute to increased phosphate levels.      

What will eat it?

  • Mostly unknown
  • Some Urchins and slugs

Ways to Treat it?

  • Manual removal or siphon removal
  • Protein Skimming
  • Water Changes
  • Phosphate Absorbing Media (GFO)
  • Refugium
  • Increase flow rates
  • UV Sterilizer

Diatoms (Brown Slime)

(Nitzschia, Licmophora)

This algae can be found anywhere there is water and grows as a “dust” on all surfaces including, glass walls, sand and rocks.  

Outbreaks usually occur at the end of the initial aquarium cycle and can grow in a variety of colors including: light brown, yellow or light red.  

Tap water, low quality salts and other silicate sources can cause re-occuring outbreaks.  During photosynthesis, bubbles of oxygen become trapped among this algae.   

What will eat it?


  • Cerith Snails
  • Nerite Snails
  • Astrea Snails
  • Trochus Snails
  • Conch Snails
  • Margarita Snails
  • Diamond Goby
  • Lawnmower Blenny

Bristle Tooth Tangs

  • Chevron
  • Kole Tang
  • Chocolate
  • Flame Fin Tomini

Ways to Treat it?

  • Siphon out
  • Strong water flow
  • Limit silicates into the aquarium: use high quality salt and RO water



Often referred to as an aquarist’s worst nightmare, this toxic,  brown or reddish, stringy algae is found in newly set-up systems.  Dinoflagellates are often confused with cyanyobacteria and diatoms and are hard  to identify. Proper identification is key to treatment of this algae.  

What will eat it?


Ways to Treat it?

  • Let it run its’ course, DO NOT perform water changes
  • Remove Turban Snails: turbo, astrea and trochus
  • Use Kalkwasser for top off water
  • Boost alkalinity
  • Use high-quality carbon
  • Use algae turf scrubber
  • Black Out

Cyanobacteria (BGA)

Commonly referred to blue-green or red slime algae, the photosynthetic bacteria, Cyanobacteria varies in color from blue-green to a deep crimson red. Cyanobacteria form mats with trapped bubbles of oxygen due to photosynthesis which can smother and kill corals.  

Common causes of outbreaks include high nutrient levels, underskimming, improper lighting, low flow, use of tap water and the addition of uncured liverock.    

What will eat it?

  • Blue-Legged Hermit Crabs
  • Conch Snails
  • Turban Snails: Turbo, Astrea and Trochus
  • Bristle Tooth Tangs:
  • Chevron
  • Kole Tang
  • Chocolate
  • Flame Fin Tomini
  • Lawnmower Blennies
  • Diamond Goby

Ways to Treat it?

  • Strong water movement
  • Protein Skimming
  • Elevate Alkalinity
  • Manual Removal
  • Activated, high-quality carbon
  • Slime Treatments and Medications  

Get these effective protein skimmers to combat even the most resilient algae blooms!
Now it’s time to treat your aquarium’s algae outbreak before it’s too late.



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