Bubble algae, commonly from the genera Valonia and Ventricaria, are green algae characterized by their smooth, bubble-like structures. While their appearance might seem intriguing, they can become a nuisance in reef aquariums due to their rapid growth and potential to outcompete corals for space.

Bubble algae are unicellular organisms that can form large, balloon-like structures. In a controlled environment, they might not pose significant issues. However, under favorable conditions, they can proliferate rapidly, covering live rock and corals, leading to aesthetic and health concerns in your reef tank.

Common Myths About Bubble Algae

  • Myth 1: Popping the bubbles releases spores, causing more algae.

    Fact: While it's commonly believed that rupturing the bubbles releases spores that float through the water column to grow elsewhere, this isn't the case. The bulbs do not contain reproductive spores and the algae spreads throughout your tank when a single bubble comes loose only to float about and settle elsewhere.  When removing Bubble Algae, it is fine to pop the Bubbles, just be sure to remove the algae entirely from your aquarium and don't leave even the smallest bubble to float about and spread. 

  • Myth 2: Bubble algae indicate poor water quality.

    Fact: Bubble algae can thrive even in tanks with good water quality. Their presence doesn't necessarily mean your water parameters are off, but maintaining optimal conditions can help control their growth.

How Bubble Algae Enter Our Tanks

Bubble algae often hitchhike into aquariums via live rock, corals, or other substrates introduced to the tank. Even a single, unnoticed cell can establish and proliferate under suitable conditions. It's usually a single bubble attached to a frag plug or a tiny bubble floating in some water that gets transferred into your tank. Bubble algae can even grow on the shells of snails and crabs and ultimately find its way into your tank. 

Preventing Bubble Algae

  • Quarantine and Clean New Additions: Before introducing new live rock or corals, inspect them thoroughly and consider a quarantine period to monitor and address any hitchhiking organisms. Physically clean frag mounts of any visible algae and consider peroxide dipping to help kill off any algae you can't see. 
  • Maintain Water Quality: Regularly test and maintain optimal water parameters. While bubble algae can grow in clean water, imbalances can exacerbate their proliferation.
  • Introduce Herbivores: Certain marine species, such as emerald crabs (Mithraculus sculptus), are known to consume bubble algae and can help keep their numbers in check.
  • Microorganisms: Boosting the population of copepods and amphipods in your aquarium is a highly effect approach.  These microorganisms help outcompete algae for resources and can ultimately make it impossible for Bubble Algae (any many other pests) to thrive. 

Managing Existing Bubble Algae Infestations

If you see even a single Bubble in your tank, it's time to take action immediately.  At this point, physical removal is still effective and there is a good chance you can defeat the algae by just removing it. If the infestation has gotten out of hand, the algae spreads faster than you can remove it and a more robust treatment plan is necessary.

  • Natural Predators:
    • Mithrax Crabs or Emerald Crabs are the most popular predators of Bubble Algae. These crabs stay small and are generally considered to be reef-safe.  While Bubble Algae isn't always their first choice, once other more palatable algae are no longer available in the aquarium, Emerald Crabs have been widely observed eating the Bubbles.
    • Another great choice for Bubble Algae control are Foxface Rabbitfish. The only downside is these fish grow up to 8" long and are best housed in larger aquariums. 
    • Lastly, you have Vlamingi Tangs which are incredible algae eaters but they grow up to 24" long and are best reserved for 200+ gallon aquariums. 
  • Physical Removal: Carefully pluck the algae using tweezers or siphon them out during water changes. Ensure you remove the entire structure to prevent regrowth. You will need to repeat this maintenance on a very regular basis to be effective.
  • Filtration & Nutrient Control: Algae, in general, will proliferate much faster in nutrient-rich environments. To help reduce the growth rate of any algae, maintain low levels of nitrate and phosphate without removing these nutrients entirely, which will adversely affect your coral.   
  • Chemical Treatments: API Algaefix is a product known to kill off Bubble Algae with repeat usage. The only downside is this same chemical will kill off many other types of algae, even macroalgae, and has been known to irritate corals. So proceed with caution and consider this is a last resort.