How To Get Rid Of Bubble Algae

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Bubble algae is something that every reef aquarist will end up fighting at some point. The large green bubbles can be attractive until they suddenly begin to take over the tank, but everyone seems to have their own solution. After a deep dive into the available information and literature, I think that we can come to some serious conclusions.

So, let’s step in and you’ll learn how to get rid of bubble algae and save your tank from rampant overgrowth.

Valonia ventricosa

Know Your Enemy

Your enemy is a bit different than other algae. Bubble algae are known as Valonia ventricosa, and they’re simple organisms that feeds off of nutrients in the water column.

Less known is the fact that bubble algae are actually single-celled organisms. Those big balls? They’re a single cell.

Valonia ventricosa is actually important for the study of microbiology due to its size. On average a mature specimen will reach about 2”(5cm) across, although some get even bigger. This allows an easier view of how chemicals pass through the membranes of cells.

We’ll get to why that’s important in a second.

Is Bubble Algae Dangerous to My Tank?

Bubble algae have a tendency to grow exponentially, and it can take over a tank. It’s not directly dangerous to any organisms, but overgrowth is a serious problem.

If the colony gets out of hand it can cover corals and equipment. Corals that are covered with bubble algae will die, the equipment can get clogged, and it will get pretty much everywhere.

If you see one or two bubbles it’s best to remove them immediately and monitor the tank for more.

I’ve seen shops selling the stuff to unsuspecting newbies. It’s a pretty shade of green we don’t see often in our tanks, but I recommend against putting it in on purpose. If you’re an advanced aquarist you may be able to check the growth and maintain it as an ornamental but I don’t think it’s worth the hassle.

To Pop or Not to Pop?

Rumor has it that popping the bubbles associated with this algae will release spores that continue to help it spread. This is taken as gospel by many people, but I’m not sure it’s the right conclusion to draw.

I’d hazard a guess that many people just missed a bubble or two during removal and it grew back.

The evidence is pretty strong in this case. 

The main thing is that herbivores are often used to control the growth of bubble algae. Most of them will pop the bubbles when eating them, rather than swallowing them whole. Herbivores would make the problem worse if that was the case.

On the other hand, Emerald Crabs pop every single bubble they eat and they’re the invertebrate that’s used to control most infestations.

Oddly, there haven’t been a lot of studies on the reproduction of bubble algae. We know that it reproduces asexually and that a mature bubble creates “daughter cells” that are eventually released from the bubble.

Or, at least that’s how Valonia ventricosa reproduces. One problem with reef-keeping is that most of us aren’t biologists and common names lead to a lot of confusion. There are about a dozen species that are called bubble algae.

Control is pretty much the same between them, but reproduction may differ between species. We can say conclusively that Valonia ventricosa doesn’t actually reproduce with spores, but popping them may release small amounts of tissue that can find purchase and grow elsewhere. The contained “daughter cells” will also be released from a mature specimen.

During my research on bubble algae I found several amateur reports with microscopes. None of them found anything resembling spores in the liquid contained in the bubbles. The studies were all done with Valonia ventricosa, and aren’t definitive but they still point to the idea that popping the bubbles isn’t a disaster.

It’s also important to remember that just because a spore is released doesn’t mean it will settle somewhere suitable to grow. Your filters, fauna, and water movement all inhibit the spores from gaining purchase. If you have adequate filtration there should be very few spores left to begin growing.

My take on this is simple: try not to pop them but if it happens don’t spend a lot of time worrying about it. There’s a lot more to worry about when you’re removing the algae than a few popped vesicles.

An Ounce of Prevention

The best way to stop bubble algae is to never let it into your tank in the first place.

Bubble algae is most often a hitchhiker. It will come on live rock or on a coral frag and then begin to grow once placed in your aquarium. Preventing the algae from getting there is far more effective than having to remove it once it’s in.

The following methods will help prevent an outbreak from occurring in the first place.

Quarantine Everything

Most people quarantine their fish, observing them for diseases and behavior problems before introducing them to the tank. Good reef keepers will also quarantine their corals and invertebrates for the same reason.

A quarantine can solve a lot of problems that happen with your tank. I’ll admit to not being the best about it, but I’ve also paid the price for not properly introducing critters in the past.

You should quarantine the following:

  • Fish
  • Invertebrates
  • Corals
  • Live Rock

A lot of people miss quarantining new live rock. You really should, since live rock can introduce more troublesome pests than bubble algae.

Every quarantine looks different, but as a general rule, I’d suggest keeping a small, cycled tank specifically for this purpose. Corals can be put on pedestals away from rocks for observation, but it’s still best to use a separate tank.

Quarantines for 1-2 weeks are a good idea, and they’ll help keep your main tank safe from more than just bubble algae.

Examine All Corals and Live Rock

During quarantine, you should be able to catch the majority of problems like bubble algae. Even before quarantining you should look over your frags and rocks carefully. Tiny bubble algae will become the big stuff if it’s not removed.

Examine the coral or rock again after quarantine to make sure there are no bubble algae or other pests present. I find it helps to use a pen light to look deep into the rocks if you have trouble seeing. 

The main species of bubble algae (Valonia ventricosa) is known for growing in low light conditions. So be thorough.

Take A Multi-Pronged Approach

Bubble algae is simple enough to control, but not everyone uses the same method. Indeed, sometimes things can be more or less effective depending on your tank’s condition and inhabitants.

The following methods are all used to take care of the problem, but you may end up needing to use more than one to handle a serious infestation.

Manual Removal

Manual removal of bubble algae is the best way to thin it out. It just takes some time if the infestation has gotten serious.

The algae will attach itself to surfaces via the use of a branching rhizome that comes from the bottom of the vesicle. This rhizome can make the algae hard to remove without popping it, but there are several ways around it.

You’ll need a tool of some sort to take care of it. I’ve seen sharpened screwdrivers used before, the last time I helped with an infestation I just used a dive knife. It just needs to be sharp, and preferably not have a strong point to avoid accidental injury to any other inhabitants.

You want to get under the large central ball and cut the rhizome back from the surface it’s growing on. On rock these branching rhizomes can get really tough, so you may have to put a bit of force into it.

On smoother surfaces, like powerhead intakes, it comes off more easily. You can often simply brush them off with a firm movement of the hand.

Remove all tissue of the bubbles if popped. This tissue can cause more bubble algae to grow, and the reason that people think popped bubbles will release a ton of spores.

If you’re worried about spores, you can run a small bit of air pump tubing near where you’re working and start a siphon into a bucket. The airline will remove a minimal amount of water, but it can remove anything released when a bubble pops by keeping it in close proximity to your tools.

Some people use a larger tube and simply let it pull the bubble algae out of the tank while they scrap them off. This isn’t a bad idea, you don’t want any loose tissue floating around. Unless you have a large tank, however, it may remove water more rapidly than you’d like.

The key is to remove all of the algae, including the attachment point. Try not to pop them, but don’t worry too much if it happens to a few of them.

Manual removal will be required in most cases, but preventing future recurrence will require other measures.

Balance Your Water Conditions

If you’ve got a massive infestation then you have problems with the nutrients in your water column.

That’s simply the truth. Bubble algae in equilibrium will make a few vesicles here and there but won’t overtake your tank. So we have to sort out the issues with your water to have a long-term solution to the problem.

Marine algae thrive in environments with high nitrates and high phosphates. It happens in the wild, and it can happen in your tank.

Lowering nitrates is simple enough.  In fact, we have published a guide on how to lower nitrates in a reef tank.

If you’re in a hurry, the essentials are:

  • Regular water changes to manually remove nitrates from the system.
  • Regular cleaning of filter socks and sponge media in filters
  • Run a protein skimmer
  • Add a refugium to the system
  • Use a pellet reactor if levels are still too high

If you do the above, you’ll be in good hands when it comes to nitrates. Any problems left if you’ve gone through all of those steps are due to one of three things:

  • High nitrates in your tap water.
  • Your tank is overstocked
  • You’re overfeeding

Acceptable levels in a reef tank are lower than 5ppm. Optimal levels are lower, roughly .25ppm.

The same methods used to reduce nitrates can also be used to reduce phosphates. The above list will also drive them down. It’s rare for phosphates to be high while nitrates are low, but it does happen.

Nitrates are needed to remove phosphates from the water, organisms have trouble uptaking the nutrient otherwise. So a situation with low nitrates and high phosphates presents a bit of a challenge.

If you’re using tap water then run a test on it before adding it to your tank. Some municipal supplies have significant phosphate levels. Reverse osmosis or distilled water should be used in reef tanks, especially if your local water has high nutrient levels.

The only different thing you can do, apart from the above methods to remove nitrate, is to use a chemical agent to bind the phosphate in the water.

You can use either a filter media designed to reduce phosphate or you can use one of the liquid phosphate removers. Both work well.

Keep working at it until your nitrates are under 5ppm and your phosphates are either undetectable or under 0.3ppm. It can take some time, so just keep removing the bubble algae manually as you balance things.

Adding Herbivores

Herbivores are a good idea to help reduce bubble algae but only if you’ve got your water balanced and have room for the increased bioload. If you don’t then herbivores can disrupt the balance of your tank further.

The most commonly used organism for controlling bubble algae is the Emerald Crab (Mithraculus sculptus). These little guys seem to love eating bubble algae and they’ll constantly seek it out. Unlike herbivorous fish, I’ve never heard of a case of one not eating bubble algae.

They’re the most commonly used animal control measure for bubble algae, but they’re not perfect. They’ll sometimes eat soft corals and may attack smaller fish, so be wary. If the crab isn’t working out you don’t necessarily need to get rid of it. They do very well in a refugium and can control any bubble algae that shows up in them.

Turbo snails are also prolific eaters of bubble algae. Any species will work, but they have small mouths and may not be able to eat the larger vesicles. If you manually remove everything you can find then they’ll be able to keep up in most cases.

You can also add fish to control algae. Fish add considerable bioload, however, and also take up a lot of room in the tank. Many herbivorous species aren’t very well suited for small to medium-sized tanks either.

And if you add an herbivore that overstocks your tank, you’ll just create more nitrates and phosphate for the bubble algae to feed on. Using fish is a bit of a gamble, but there are some success stories with large tanks.

Fish also tend to be hit-or-miss. Some will immediately go after bubble algae, others may studiously ignore it despite being the same species.

Some of the species used to control bubble algae are:

  • Tangs
  • Rabbitfish
  • Blennies
  • Angelfish
  • Surgeonfish

Fish in these species are herbivorous and most will eat bubble algae. Just keep an eye on their progress and make sure to have a plan if anyone gets aggressive with their tank mates. I would try with invertebrates before attempting to use a fish, it’s cheaper and less likely to cause serious problems in the tank.

Herbivores don’t fix your water quality. You still need to balance the tank’s nitrates and phosphates for long-term success in keeping bubble algae out of the tank.

That said, they’ll help control any future infestations and they’ll often find the smaller vesicles before you do. The sooner the algae end up in your crab, snail, or fish’s belly the better!

UV Sterilizer

UV sterilizers are sometimes adopted as a countering method for bubble algae. The basic idea is that it can kill the “spores” in the water.

A good UV sterilizer can help, but killing the bubble algae in the water isn’t easy. After installing the sterilizer you should run it at the lowest possible flow rate that it’s rated for. This gives it more time to kill anything lurking in the water column.

This is only part of a strategy. A UV sterilizer won’t affect the matter already in the tank, and it’s not going to create better conditions to prevent the future spread of the bubble algae.

Refugium

If you’re not running a refugium… well, you should be! They’re useful for a lot of things in your tank. They help clean water, keep your pH even, and provide more water for the system overall if built separately from the main sump.

The overall effect is that a refugium helps clean out the excess nitrates that can cause explosions of bubble algae.

Setting one up is simple, just run the pumps and pop in some form of macroalgae. Chaetomorpha is easy to take care of and is used by many people. The macroalgae are just there to uptake extra nutrients and help scrub the water column.

On a similar note, it’s a good idea to encourage coralline algae in your tanks. This isn’t just beneficial for the corals, it also snatches up real estate to prevent the bubble algae from spreading too far.

Bottom line is that maintaining a refugium is a great idea for your tank. With enough macroalgae, you can starve out the dreaded bubbles.

Reduce Waterborne Nutrients With RO or Distilled Water

Reverse osmosis or distilled water should already be used in your tank. Full stop. Reef tanks are too delicate to mess around with the municipal water supply. Not only does it contain chlorine, but it can also contain considerable amounts of nitrate and phosphate.

Water changes don’t help much if the water coming in has a higher nitrate level than the water going out.

Changes can also happen to the water supply. You can use the EPA’s website to get a water report for your local area. You may be surprised at how much is in there.

When it comes down to distilled water versus reverse osmosis there’s no functional difference in your tank… as long as the RO water was treated properly. Unless you’re personally testing the water then you can’t be sure.

Distilled water should have 0 total dissolved solids but sometimes tests at very low levels. It’s the better choice if you’re buying your water at the store. If you have a well-maintained RO filter at home it can also be used, but make sure to stay on top of filter changes.

Bottom line is that distilled water is more consistent in not containing nitrates or phosphates, but RO water is fine as long as the filters were changed at the right time. Either is far superior to tap water and you should be using them whether or not you have an algae problem.

Big Bubbles, Small Problem

The majority of learning how to get rid of bubble algae is just maintaining your tank properly and removing it by hand. Herbivores can help as well. Bubble algae blooms are a pain, but they’re easy to manage as long as you take care of the above.

The best time to act is now, so start weeding today and figure out the source of the problem!