The infestation of Bubble algae is definitely one of the worst scenarios you can encounter in a heavily stocked reef aquarium.
Bubble algae exist as unicellular organisms with spherical or elongated fluid-filled thallus or thalli. They are usually green in color; pale/light green to emerald or dark green, a red species of bubble algae also exists, it is called Red Valonia (Botryocladia skottsbergii).
These beautiful but destructive algae should be removed as soon as they are detected in an aquarium, otherwise, they will feed off the nutrients in the tank water to grow more and spread aggressively, they also have the ability to overrun the tank causing discomfort to the inhabitants.
Bubble algae consist of various species that have similar features, for example: bubble-like structure, absence of stem, presence of small roots for anchorage, and reproduction by spores.
In this article, we will discuss the diverse varieties of Bubble algae and how to effectively get rid of them.
What Are Bubble Algae?
Bubble algae are a group of single-celled organisms belonging to the phylum Chlorophyta. This is a taxon of green algae otherwise known as chlorophytes. It is believed to be one of the largest single-celled organisms in the world.
Bubble algae inhabit only in saltwater in the tropical and subtropic regions and can be found throughout the Caribbean, the Pacific, and Indian Oceans. These algae are characterized by a light green to dark green coloration, however, they can appear to be silver, teal, or blackish in the water column due to certain factors that make them to be reflective.
The cell of bubble algae possesses multiple nuclei and chloroplasts, which allows it to thrive and perform photosynthesis in its natural habitat and in reef tanks.
Bubble algae have varying structural forms which range from ovoid to spherical, some have the look of an orb or tennis ball. This spherical body or thallus is attached to substrate or decorations by tiny hair-like appendages (rhizoids), giving it a firm hold. The thallus is an enclosure of a thin-walled, tough, multinucleate cell with a diameter of 0.4 to 1.6 inches (typical) and up to 2 inches (5 cm).
This type of algae grows individually and in clusters, they reproduce by means of cell division. This involves a process by which the multinucleate parent cell divides to produce new cells and these cells develop into bubbles.
How do Bubble Algae get into the tank?
In most cases, Bubble algae make its way into reef aquariums by hitchhiking on newly imported live rock. At first, they can be totally undetected because of its form as tiny spores attached to the rocks. However, they get bigger with time to form bubble-like structures all over the rock and substrate.
A good practice in averting a potential Bubble algae outbreak is to quarantine new live rock and other reef aquarium ornaments before placing them into the tank.
You can also use this opportunity to scout for any visible vesicle on the body of the rock and remove them immediately. Also, make it a habit to inspect coral plugs and discs to which corals are attached to since they are also prone to algae attachment.
Can Bubble Algae Harm Corals?
Eventually, yes. Bubble algae will harm your corals. Although these algae are not poisonous per say; you will notice them growing on the edges of your corals.
Slowly but surely, the bubbles will begin to spread and smother the corals by covering the whole surface including the stems.
These algae may look cool at first, but they can rapidly grow to nuisance proportions.
Therefore, do not make a mistake of thinking that Bubble algae are that bad. You need to remove it ASAP. These algae can ruin a reef tank if not dealt with quickly. It is not a normal part of a healthy reef system.
Varieties of Bubble Algae
Green bubble algae are not the only species that can be found in our saltwater tanks. Actually, there are can be several types of bubble algae. Different species will grow to different sizes and shapes.
This is unarguably the most renowned bubble algae variety predominant in reef aquariums. It was formerly known as Valonia ventricosa and renamed to Ventricaria ventricosa, with it being the only alga in the genus Ventricaria.
Note: Also known as ‘Dead sailor’s eyeballs’ or ‘Sea Pearl Algae’.
This alga is characterized by a single, fluid-filled, and rounded bladder or thallus. Unlike most bubble algae varieties, this variety occurs in single forms, meaning that it does not branch off daughter vesicles.
Each bladder grows and thrives solely while anchoring firmly on the substrate or hard surfaces in the tank, it is highly tolerant of low light levels. The dark-green spherical bladders of Ventricaria ventricosa can grow to nearly 2 inches (5 cm) in diameter and the cell wall appears to be very smooth despite its toughness. This feature makes it undesirable for herbivores.
Ventricaria ventricosa has a wide distribution range, it can be seen around the Indian & Pacific Oceans, the Samoas, Australia, and the Caribbean.
Features: Large bubbles that grow singly and/or in clusters.
This variety is characterized by elongated bladders / vesicles of about 2 inches (5 cm) length and an inch in width, they grow in small unbranched clusters with all the bladders connected to a single root structure for anchorage.
Boergesenia exhibits an epiphytic behavior in the sense that it can grow on other organisms like algae, coral, and sponges.
Its cell wall is less hardy than that of Ventricaria ventricosa.
Features: Elongated bubbles clustered. Small clusters compared to other species.
Valonia aegagropila features a small, densely packed, unicellular bladders with a visibly dark to olive green coloration. They do not occur in single life forms like the Ventricaria ventricosa, rather they branch off tiny bladders which are a few millimeters in size.
The clusters are compact and this makes it almost impossible to manually remove them without it bursting and releasing spores in the water column. Valonia aegagropila has a wide geographical distribution in tropics and subtropics of the world.
Features: Small bubbles that grow in dense clusters.
Valonia utricularis has elongated and slightly curved branching bladders, these bladders grow in compact clusters which are firmly interconnected.
The vesicles are about 2 inches in length and ½ inch in diameter, its membrane is very delicate and capable of rupturing easily when you try to remove them from the rock.
Features: Elongated bubbles that grow in dense clusters.
This species is similar to Valonia utricularis, it forms dark green, branching, single-celled bladders less than ½ inch thick and up to an inch in length. The vesicles are smaller and clavate; with a swelling or slight distortion at the top end.
Valonia macrophysa can be found throughout the globe; in the Indian Ocean, Pacific, the Caribbean and Mediterranean, and extending to the Canary Islands in the eastern Atlantic.
Features: Small clustered, elongated bubbles
An unusual bubble algae species, Dictysophaeria cavernosa forms an irregular shaped, grainy textured group of unicellular bubble algae, approximately 1 inch (2.5 cm) across.
The bladder deflates / ruptures when it matures, and this unveils the miniature cells that make up the thallus walls. It is distributed across the Indian Ocean to the Western Pacific, extending to Polynesia and throughout the Caribbean.
Features: Pitted-looking bubbles.
Control of Bubble Algae in the aquarium
Do not think that Bubble algae will disappear on its own. Unfortunately, it will not happen.
Getting rid of Bubble algae in the aquarium can be quite time-tasking and laborious, its presence in large numbers can be horrifying and it is capable of dominating your reef tank in the long run.
Let’s take a look at some of the effective methods of eliminating bubble algae in the aquarium.
- Manual removal
- nutrients and resources restriction
- Natural Predators
This is a proven way of eliminating bubble algae as soon as they show up.
This should be done carefully using your fingers or a sharpened flathead screwdriver to dislodge the vesicles gently from the roots attached to a rock. DO NOT scrub bubble algae! Afterward, carefully remove the vesicles from the tank. If you cut off just the top and leave the base it will grow back.
The point is that popping green bubble algae in the tank creates a negative effect by causing more to grow in other places due to spores being released into the water column.
Note: The bubbles possess cystocarps that are capable of producing spores that get into the water when a mature bubble alga ruptures.
However, do not panic, even if you popped some of them. In a situation whereby the fluid-filled bladders ruptures during the removal process, you can use a siphon hose to draw off the spores deposited into the tank water to prevent further spread.
It is detrimental for spores to be liberated into the water column, and this usually occurs when a mature vesicle or bladder of bubble algae ruptures during removal.
This view is solely true for members of Order Valoniaceae, the vesicles can only bear spores when they reach maturity; about one-third of its final size. But the good thing is that they still have to go through the stress of bypassing filter feeders and the filtration system, and also finding a suitable position to comfortably settle.
Another alternative is to move the infested rock to a clean basin of saltwater, there, the bladders can be removed easily. After the exercise, the rock should be adequately rinsed with tank water and placed back into the tank.
Tip: Make sure that you turn off all pumps and power heads inside of your tank. So, if we do cut or squeeze it and it breaks and releases all those spores, they will not blow all over your tank.
Is Popping Bubbles a Myth?
On the Internet, you can find feedbacks where people are not afraid to squeeze the Bubble algae. According to their experience, the fact that these algae can contain gametes is exaggerated and it is not as dangerous as people think.
Personally, I may agree with them only when these spores are quickly pulled from the tank (siphon) or consumed in a closed aquarium setup in a nearby future.
According to the study, Bubble algae have the ability to regenerate new cells from fragments of cytoplasm. However, to do so these algae need 2 – 3 hours.
- Invertebrates: Invertebrates like the Emerald green crab (Mithrax sculpture) is a good predator that will tear up and consume most bubble algae species. The downside is that they are omnivorous, and as such they might feast on corals and snails.
Another underlying problem is that once they rupture the bladders before chewing them, algae cells get released into the tank water, but that is not really a big problem if you have a good filtration system installed.
Other invertebrates like herbivorous snails, Turbo spp., and Trochus spp., will eat young some species of bubble algae and newly-settled spores.
In addition, Ercolania endophytophaga is very hostile towards Bubble algae of the genus It is capable of penetrating a vesicle without tearing it, eating the tissue and spores from the inside.
- Fish: Rabbitfish, Tangs, and Surgeonfishes of the Zebrasoma genus are all up to the task when it comes to devouring Bubble algae in reef tanks.
However, these fish types tend to exhibit territorial behavior and are not ideal for small reef tanks.
- Urchins like Diadema setosum will also consume smaller Bubble algae vesicles, but this is only done as a last resort if no other algae are present in the reef tank to satisfy their cravings. Another problem is that they can be a bulldozer to corals.
If your tank is completely covered with Bubble algae and your algae-eaters are losing the battle, this can be the next way of protecting the reef tank if nothing else works.
Vibrant Liquid and Bubble Algae
Vibrant is a new revolutionary liquid aquarium cleaner. Even though it was not specifically created to combat Bubble algae problems in saltwater tanks, it is still so potent that lots of aquarists use it for these purposes.
- Add 1ml of Vibrant per 10 gallons (~40 liters) of aquarium water once per week.
- If you have too much Bubble algae, you can dose it twice a week.
Vibrant takes a while to get rid of Bubble algae, but it does work. Approximately in 3 – 4 weeks bubbles turn grey and completely disappear in the next few weeks. DO NOT overdose, you have to be patient.
Note: Vibrant is safe with all fish, corals, and invertebrates.
Downside: After dosing Vibrant, there is a chance of a Dino bloom. It can also kill Cheato in the tank. So, it might be better to remove it during treatment..
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Bubble Algae and Hydrogen Peroxide
- Carefully pluck Bubble algae and scrape vicinity. Do it out of water.
- Apply hydrogen peroxide directly to the affected areas. Do it out of water.
- Wait about 2 – 3 minutes. Do not put it in the water.
- Rinse the frag in saltwater.
- Put it back in the tank.
If it is not possible to remove the rock from the tank, you can try to spot treat Bubble algae with a syringe. Just go right up and squirt it. Wait a day and see how potent it was.
Be careful, shrimp are really sensitive to H2O2. They can come to the treatment zone and see what is happening and it will harm them!
Note: Don’t forget to turn off the flow during and after (10 – 15 min) treatment.
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Dipping Bubble Algae Outside of Tank
Some aquarists use 1:1 ratio. Well, I prefer to go slow, conservative, and safe. Therefore, I use a 4:1 ratio of hydrogen peroxide (3%) for 5 minutes.
- Swirl occasionally.
- Remove and rinse.
- Return to the tank.
Freshwater dip vs Bubble Algae
Do not waste your time. Freshwater dips will not do anything for Bubble algae.
Blackout vs Bubble Algae
I have seen many questions on forums where people ask – will blackout kill Bubble algae? Has anyone had success in killing algae off by blacking out the tank? Etc.
Unfortunately, blackouts will not help with Bubble algae.
Even 3 – 4 days blackouts are pretty inefficient against these algae. Bubble algae can grow well in very low nutrient systems. They can even grow on the inside of powerheads and overflows in complete darkness!
Even though these algae may not spread and grow very fast but it is still not a remedy. Bubble algae do not require lots of light to thrive.
How to Prevent Bubble algae. Nutrients Restriction
Lots of articles mention that nutrients restriction is one of the ways to get rid of Bubble algae.
This is not true.
It is very hard (impossible) to defeat Bubble algae by only reducing nutrients or in any other way that does not involve physical removal by you or another organism that eats them.
However, it is still a good way to prevent a breakout and spread of an existing one.
It is an effective method of controlling the spread of bubble algae is by limiting the nutrients they need for growth and survival. It is important to introduce ornamental algae species to compete with Bubble algae for the much needed available resources – light, nutrients, and space.
Good examples are Chaetomorpha, the unicellular green alga Caulerpa species, other worthy mentions are the calcareous green and red algae species: Halimeda and Coralline algae. These algae species are fast-growing and ideal for scrubbing nutrients from the tank water.
Coralline algae, sponges, and stony corals all serve as potential competitors for nutrients and space in the tank since they are able to effectively outcompete and overgrow the aggressive bubble algae.
Keep your water parameters stable; maintain the nitrate and phosphate levels near 0 (these are their main food sources).
Note: Many aquarists say that their water perimeters are perfect. They have no phosphates, no nitrates but Bubble algae still show up in the tanks. Well, we have to keep in mind that almost every phosphate test kit on the market tests for inorganic phosphate. Unfortunately, organic sources are not detected in any kit that does not use an enzyme to break down organic phosphates first.
Therefore, it is important to:
- change your filter media regularly,
- carry out partial water changes weekly or biweekly using RO water,
- remove excess nutrients through protein skimming.
This will remove a lot of the organics that decompose into nitrates to feed Bubble algae.
Do not buy anything in the store even if a frag that has visible Bubble algae growing on it.
Bubble algae are a nuisance in reef aquariums. They multiply and spread rapidly by releasing spores in the tank water. These algae dwell in the tank by attaching itself firmly to hardscape; rocks and decorations, some species of bubble algae can grow on other organisms as well.
The best preventive measure is to quarantine newly imported live rocks in order to eliminate spores of bubble algae and also by handpicking visible vesicles if any.
Bubble algae can be effectively controlled by denying them the essential nutrients they require for growth and survival, natural predators should be introduced to help keep the existing algae under control by preying on them. It can feel like an uphill battle some days, but you do eventually make progress.