Bubble Algae (Valonia): Causes and Control Methods

Introduction

Bubble algae (Valonia) are green spherical algae that can become a serious problem in marine aquariums. In some systems, their reproduction takes on the character of a true epidemic, when they literally overrun the entire aquarium. Fighting bubble algae can be challenging, and aquarists sometimes resort to extreme methods, even attempting to trigger cyanobacteria blooms to cover all surfaces and deprive Valonia of light.

Nature of the Problem

The problem with bubble algae can be extremely serious. In advanced cases:

• Flow pumps become clogged with bubble algae balls in a single day to such an extent that they must be removed and cleaned every evening
• Without daily cleaning, water flow can practically stop
• The entire reef becomes covered with green balls
• Bubble algae can reproduce hundreds of bubbles per day

This happens even in systems where the main parameters (nitrates, phosphates) are normal.

Conditions for Bubble Algae Development

Conditions that bubble algae prefer:

Stagnant Water

• Systems with poor water flow
• Substrate heavily contaminated with detritus
• Insufficient circulation between display and sump

Slightly Lowered pH

• Bubble algae thrives at pH around 8.0 and below
• At pH below 8.3, bubble algae can flourish even if corals are growing normally

Organic Substances

• Bubble algae actively consumes organics dissolved in water
• Especially effectively absorbs powdered coral foods
• Can feed on the same substances as corals

"Old" Water

• Bubble algae prefers established aquariums
• It develops more poorly in clean systems with regular water changes

Myths About Bubble Algae

There are many myths about bubble algae that have no scientific basis but are common among aquarists.

Myth 1: "Don't Squeeze Bubble Algae Balls"

There's a widespread belief that if you squeeze a bubble algae ball, liquid with spores will come out and spread bubble algae throughout the aquarium. This isn't entirely accurate.

Reality: Bubble algae doesn't reproduce via spores in the way people imagine. When you squeeze a bubble, the contents released can indeed serve as nutrients for remaining bubble algae. However, this isn't "infecting" the aquarium with spores, but simply releasing nutrients.

Myth 2: "Bubble Algae Appears Due to High Nitrates and Phosphates"

Many consider high levels of nitrates and phosphates to be the main cause of bubble algae development.

Reality: Although bubble algae consumes nitrates and phosphates, these parameters aren't determining factors. There are many aquariums with high nitrate and phosphate levels where bubble algae is absent. Conversely, it can thrive in systems with low values of these parameters.

How Bubble Algae Reproduces

Bubble algae reproduces through division and growth of small bubbles:

1. Tiny microscopic bubbles can separate from larger ones
2. They quickly attach to surfaces (approximately a day)
3. A colony of new bubbles begins to develop from a small bubble
4. The bubbles increase in size
5. When they reach a certain size, they can detach, scatter, and form new colonies

When you crush a bubble algae ball, the released liquid doesn't contain special "spores," but is a nutrient medium easily absorbed by remaining bubble algae, promoting its growth. A similar process occurs with Caulerpa when it turns white, sheds its green coloration, and the water becomes cloudy with chlorophyll. It appears dead but then begins to rapidly reproduce from small offshoots. Essentially, Caulerpa is simply restarting itself - by dying and decaying, it provides resources for new young growth.

Methods of Controlling Bubble Algae

1. Improving Maintenance Conditions

The main control method is creating unfavorable conditions for bubble algae:

Increasing Flow Through the Skimmer

• Strengthening filtration
• More intensive skimming
• Depriving bubble algae of nutrients

Raising pH

• Bringing pH to 8.3-8.4
• At this level, bubble algae naturally begins to pale and die off
• It's important to raise pH through natural methods, not chemical additives

Regular Water Changes

• Refreshing the system
• Removing dissolved organics
• Stabilizing parameters

Strengthening Biofiltration

• Developing beneficial microflora
• Creating competition for bubble algae for nutrients

2. Biological Methods

There are several organisms that can effectively combat bubble algae:

Emerald Crabs (Mithrax sculptus)

• Effectiveness: moderate
• Disadvantages: can damage corals, especially males with large claws
• Recommendations:
  • If using them, choose females with small claws
  • Females have a wide tail on the underside
  • Males with narrow tails and large claws are more aggressive

Black Crabs with Spoon-shaped Claws

• Effectiveness: high
• Disadvantages: minimal, rarely damage corals
• Characteristics:
  • Flattened claw ends in spoon shapes
  • More agile than emerald crabs
  • Specialize in scraping algae from surfaces

Naso elegans or Naso lituratus (Elegance or Lipstick Tang)

• Effectiveness: very high, best solution
• Disadvantages: requires a fairly large aquarium
• Characteristics:
  • Naso elegans (known as Naso blondi) — with orange dorsal fin
  • Naso lituratus — with black dorsal fin
  • Fish as small as 7-8 cm already effectively eat bubble algae
  • A large specimen (about 15 cm) can completely clean a heavily overgrown aquarium in 1-2 months
  • Never damages corals
  • Consistently feeds only on algae

Rabbitfish (Siganus vulpinus, Siganus unimaculatus, etc.)

• Effectiveness: high
• Disadvantages: sometimes may nibble at zoanthids and soft corals
• Characteristics:
  • Good at eating bubble algae
  • Less reliable than tangs

Prevention

The best way to fight bubble algae is prevention:

1. Maintain good water circulation
2. Ensure effective biofiltration
3. Monitor pH level (aim for 8.2-8.4)
4. Regularly perform water changes
5. Prevent formation of stagnant zones
6. Control feeding, don't overfeed the system

Conclusion

Bubble algae is not such an invincible enemy if you understand the causes of its appearance and methods of control. Raising pH to 8.3-8.4, improving water flow and biofiltration, along with using biological helpers (especially Naso elegans/lituratus) is a comprehensive solution that in most cases leads to complete elimination of this problem.

As with other unwanted organisms (such as aiptasia), the key question is not how to destroy bubble algae, but why it appeared and thrives in your particular system. By eliminating the root cause, you'll not only get rid of the current problem but also prevent its return in the future.