Nuisance Algae ID Guide:

Unless you have a nuisance macro algae that is unusual, (or something I don't consider a pest because I am partial to algae), we hopefully got you covered. We need photos to continue the guide so send them in if you have a question. We can probably identify the nuisance algae you are facing.

This guide is a tool for aquarium hobbyists, and is not a scientific resource. Often cyanobacteria rears its ugly head even though it is not an algae. But since most people look for a red slime algae when they want to find "cyano" (we use hobby terms as well), it makes sense to include them in an "Algae Guide". Same for a lot of other things, "cyano" only refers to a certain set of species of cyanobacteria that seem to appear in every tank, but in reality there are thousands of species of cyanobacteria etc.... Well that is about it. If you have questions about a nuisance algae contact us.

Diatoms

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Almost sure to appear in a new system, diatoms are some of the most abundant organisms on earth. They usually surface in the aquarium as a brown powdery like substance, within a week or so after a tank finishes its cycle. Diatoms feed on available silicates in your system and will run their course in time. Similarly, because they feed on silicates, anytime you add new sand, rock or something plastic they can pop up.

Manual Removal - Diatoms are easily wiped from the glass with a mag float, a turkey baster or a toothbrush can access other areas of the tank. Be prepared for them to re-establish themselves quickly, they are likely to be able to resettle and have amazingly fast growth rates.

Clean Up Crew- Ceriths, Nerites and Chitons are effective at removing diatoms as well as the algae species that usually replace them as the silicates in your system are depleted.

 

Red Slime, Cyano, Cyanobacteria

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"Cyano" as it is commonly referred to is one or more species of cyanobatceria. It occurs commonly in almost every reef tank at some point, and is caused or encouraged by a number of reasons including:

Available nutrients - Especially phosphates and iron in this case.
Low flow/Dead Zone - Cyano prefers growing in low flow areas.
Warmer Water - Cyano tends to grow faster in warmer water than in cooler water
Low Alkalinity- While not a cause, higher alkalinity tends to discourage cyano growth.
Possible "contaminated" water source like tap water, that has nutrients fueling the outbreak

Manual Removal: Wipe glass with mag float, light toothbrush hardier corals and the rocks. Cyano on the sand can sometimes be pulled off as a mat and discarded. You should use a net or a siphon to remove the cyano dislodged by the toothbrush. Don't be discouraged if it comes right back, cyano grows fast and is extremely efficient at consuming nutrients.On the bright side, it should die off once nutrients are managed.

 

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Increase water changes to 30% a week with a high quality water source, such as distilled or RO/DI water. Be aggressive about removing any rotting organics in your tank that may be contributing to its growth.

Starving it out : Use a phosban reactor, or granulated ferric oxide to remove excess phosphates in the system. Check to make sure you are not feeding any foods that are particularly phosphate rich. Almost all foods when converted by animals will add to the tank's phosphates levels, but prepared foods like seasoned nori, liquified foods, gels and low quality fish meals tend to be higher in phosphates than other foods. Such feedings should be suspended or stopped if possible until the outbreak is under control.

Chaeto and other macroalgae will help maintain parameters to keep cyano from forming, but because cyano is an epiphyte, (can grow on other life forms), it may starve your desirable algae from light. During an outbreak make sure to keep you macro clean so it can receive light and survive the ordeal.Chemical products exist to remove it, make sure to take into account for possible hypoxia issues. 

 

Green Film Algae, Film Algae

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This green powdery film, or cloudiness is caused by a variety of species of microalgae. It is fairly common in tanks of all ages, and tends to be present in some degree at all times. It is only when a bloom occurs that the microalgae becomes so dense as to become noticable.

Clean Up Crew- Ceriths, Nerites, Astraea spp., most limpets and chitons. Many different species of copepods, amphipods and isopods will feed on film algae as well. Hermit crabs pick at it but are rarely effective against film algae.

Why it happened - Available nutrients and you get a bloom. Don't get too worried, it is pretty common to get some spots every now and again. You may notice some tank cloudiness too, same thing (micro algae). Chronic problems are another thing, get your phosphate or nitrates down, with a refugium that grows macroalgae, a DSB, a GFO (Granular Ferric Oxide)reactor etc...

Starving it out - Starving it out : Use a phosban reactor, or granulated ferric oxide to remove excess phosphates in the system. Check to make sure you are not feeding any foods that are particularly phosphate rich, or are feeding too much.

Manual Removal - This algae is pretty much the reason they invented the Mag-Float. Time to break it out. A toothbrush will work on the rocks. Change the water, after blasting the rocks with a turkey baster to stir up sediment that may be decaying and adding to nutrients.

Tip - Pods seem to thrive on it and it recharges the microfauna in the system which will actively feed on the small algae. Extended or large blooms are another story, as it can begin to limit light penetration.

  

Green Hair Algae

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Green Hair Algae or "GHA" is really a broad term that covers hundreds of species of green simple filamentous algae. These species tend to be simple, fine in texture, and have few distinguishable features. True species level identification requires a microscope.

Distinguishing it from look-a-likes:GHA is not coarse or wiry, it should break apart easily when pulled, and should lose form quickly when removed from water. If you can make out a root structure, or a stiff branching structure it is probably not GHA.

Manual Removal - Green hair algae can be pulled out easily, and tooth brushed or scrubbed off the rock work. This is easier to do if the rock is outside of the tank. If it is growing from the sand sift it out with a net.

Clean Up Crew- Assorted Hermits, Blue Legs, Florida Ceriths, Chitons, Turbograzers, Sea Hares, Conchs, Emerald Crabs, Urchins and a few others. It is readily accepted by many herbivores, but because it grows quickly it may persist even in a tank with a fair amount of cleaners.

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Why it Happened -An excess of available nutrients, particular the majors like phosphates and nitrates. Keep an eye on possible iron and potassium sources which may also help fuel hair algae. Hair algae spores and fragments are so abundant that keeping it out of the tank via quarantine is unlikely to be successful. Your best bet to preventing this algae from taking hold is to maintain a weekly water change regimen, maintain your filtration and perform manual/natural algae removal as it forms. Proper magnesium and alkalinity levels are thought to discourage the growth of many species of GHA.

Starving it out - Use a phosban reactor or a macroalgae like chaeto to reduce nutrients. Increase the frequency of your water change routine, taking the opportunity to siphon out as much hair algae as you can each time. Older light bulbs tend to drift towards the red spectrum, and fuel the growth of hair algae so considered replacing them if need be.

Green Turf Algae

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What is known as "Green Turf Algae" in the hobby is really a generic name given to hundreds of different species of macroalgae that describe certain similar characteristics. They are coarse, wiry, and generally have thicker wider blades than Green Hair Algae. They may or may not have a mat like root structure, sometimes they just seem to sprout from the rock.

Turf algae that sprouts directly from the rock can be a pain to control, as it is difficult if not impossible to pluck it all. Once discovered it should be treated outside of the aquarium, perhaps by dipping the affected rock or frag in water treated with an algaecide.Turf algae that grows with a "root" mat can be peeled by pushing down on the algae as you scrape your thumb against the rock dislodging it in one swoop. Let it get big enough so you have leverage. The 3reef member who removed this piece did it perfectly.

Clean up Crew members that will eat Green Turf Algae include inverts with considerable cutting power like urchins, chitons, and emerald crabs.

Bryopsis pennata and B. plumosa

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Some of the hardest to remove common species of macroalgae encountered in the hobby are B. pennata and B. plumosa. These two species have noticeable discernible midribs (center portion of the algae), that are wider than their branches. They also form a mat like root system on the rocks.

B. pennata (pictured on the left) has irregular and more sparse branching than its closely related cousin B. plumosa which has more symmetrical and fuller branching. (picture coming)There are many, many species of Green Hair Algae that have feathery branching, and are not necessarily members od the Bryopsis genus, nevermind B. pennata and B. plumosa. Simply because the hair algae in your system has branches does not mean it is one of these algae species.

The reason hobbyists despise finding this algae in their tank is because cleaner crews rarely finish it off when they snack on it. Sea hares, nudibranchs, urchins, emerald crabs, chitons, and even the larger Astrae tuber will nip at both of these species, but rarely consume it with any effectiveness.

If you do confirm you have Bryopsis:

1. Try to get on it quickly. If it is only on one rock remove the rock, remove algae, starve of light in a QT.
2. Manual Removal - If that doesn't work or get it all, remove all you can by hand. People will tell you not to do this because it will spread. Let me assure you, left untreated bryopsis will spread. Just be careful about it, and if you can pull the rock out to remove it all the better. If takes hold in the sand sift it out with a net. If you don't remove the base of bryopsis you are wasting your time.
3. Starve it out - As always if you can get down nutrients nuisance algae has a harder time taking hold, or coming back after manual removal.
4. Repeat steps 2 & 3 aggressively.
5. If that doesn't work try raising your magnesium to very high levels. I don't want to be blamed if this causes losses in your tank, many people have done this with great success and minimal stress, but still....please do your research and don't blame me if something goes wrong. alt I say QT.

Bubble Algae, Valonia

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Usually a member of the Valonia genus, this fast spreading algae can go from just a few "plants" to covering the tank in a short amount of time. Because of this you will want to treat it quickly, before the algae has the opportunity to send spores throughout your system.

Manual Removal - Don't be clumsy and spread this one. Get them small, cover them with a baster, scrape the baster along the rock, and when the Valonia comes off release the plunger and suck it up. Discard and repeat. If you have a lot to do, by the time you are done you will be ready to add new mixed water to complete the water change. Be aggressive with your manual removal.

Clean Up Crew - Emerald and Ruby Crabs will eat it, as well as certain Rabbitfish. Juvenile Emeralds are better for the task, the smaller the better. Get one per handful amount of bubble algae.

It is fairly easy to keep this species out of the aquarium by inspecting rock and frags added to your tank.

Lobophora

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Brown semi rigid but slippery macro algae. Often confused with plating coralline, the slippery rubbery feel is a give away if you don't want to use scientific methods to determine the id. Can be highly varibale both in color and in formation. Can be red or yellow, and can grow in saucer like shapes, (pictured to the left), or in a ruffled ribbon formation.

Manual Removal - Difficult. Qting the rock in an extended dark cycle is the best way. Good thing it doesn't spread rock to rock too fast. A chisel or a flexible knife like a putty blade works, but you got to get it all, and take some of the rock just to be sure.

Clean Up Crew- Emerald Crabs (best bet here), Sea Hares, some Turbos, Chitons, Limpets, Tangs, Urchins, will pick at it, but it is likely to persist, but at least it will be controlled.

Why it happened -
You didn't quarantine, and you have available nutrients for it.

Blue Green Cyano

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Forms a slimy mat of green goop for lack of a better term. Usually dark green despite name.

While it should be treated like regular cyano, this stuff is generally more difficult to get rid of because most clean up crew species are uninterested in it. Chitons, limpets, and nerites can eat it, but dont expect them to do the whole job for you.

Manual Removal: Wipe glass with mag float, light toothbrush hardier corals and the rocks. Cyano on the sand can sometimes be pulled off as a mat and discarded. You should use a net or a siphon to remove the cyano dislodged by the toothbrush. Don't be discouraged if it comes right back, cyano grows fast and is extremely efficient at consuming nutrients. To make matters worse, species under this heading seem better at handling nutrient lulls than other forms of nuisance algae.

Starving it out : Use a phosban reactor, or granulated ferric oxide to remove excess phosphates in the system. Check to make sure you are not feeding any foods that are particularly phosphate rich. Almost all foods when converted by animals will add to the tank's phosphates levels, but prepared foods like seasoned nori and low quality fish meals tend to be higher in phosphates than other foods. Liquefied foods tend to have more waste than others, plankton cultures that haven't matured can lead to blooms as well. Such feedings should be suspended or stopped if possible until the outbreak is under control.

Chaeto and other macroalgae will help maintain parameters to keep cyano from forming, but because cyano is an epiphyte, (can grow on other life forms), it may starve your desirable algae from light. During an outbreak make sure to keep you macro clean so it can receive light and survive the ordeal.Chemical products exist to remove it, make sure to take into account for possible hypoxia issues. This can usually be done by heavy surface agitation to ensure oxygen levels remain adequate.

 You can find the Greeny Cyano cleaners we have in stock here.

Dinoflagellates

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This light brownish menace feels like snot growing up from the rock or sand, with trapped air bubbles in it. Not to be confused with algae that has an air bubble that has landed on it, dinos make them. Not all species of dinos are bad the one pictured is though, and has caused many aquarists to tear down their tanks. Also, it is questionable as to whether "dinos" arent really just a cyanobacteria species, but that is how the hobby goes and this isnt a scientific resource.

Manual Removal - Remove the rock and place it in a large saucepan. Add water enough to cover the rock. Boil the tar out of it. Rinse and repeat with scrubbing in between. Let dry for 3 days in sun. alt Okay maybe not that far, but.... it is hard to remove. Scrub it as best you can.
Clean Up Crew -Don't bother.


Starving it out - Increase skimming, use a phosban reactor, or a macro like chaeto to take down nutrients. Some people have had success treating "dinos" by raising their ph and alk, but if you do so, do it with caution.

 

Calothrix

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These species of cyano often appear as a light slimy yet hairy/fuzzy nastiness that loosely attaches to your rock work. Air bubbles are usually trapped while eascaping the "algae", just like in the picture to the left. Calothrix is a type of blue green algae that looks very similar to Dinos. We have them next to each other in the guide to help you distinguish the difference between the two.

Manual Removal - Remove the rock and scrub, and then fine tune with a toothbrush. Let the cleaners get the rest. It helps to use a net to collect the debris that will occur as a result of the toothbrushing.

Clean Up Crew - Chitons, Nerites and we are looking into others.

Starving it out - Use a phosban reactor or a macro like chaeto to take down phosphate. If you have a nitrate problem too, you can add more live rock or rubble to the tank, do some more wcs, add macro, add dsb, etc...

 

Gelidium, Red Wiry Turf Algae

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Many species of short creeping red algae exist so the hobby generally lumps all of them under the heading "Gelidium", (the genus that is home to many of those species), and the common name Red Turf Algae, or Red Wiry Algae.

Manual Removal - Difficult. Macros that have fragile runners and creep along the rock are the hardest to manually remove. Do the best you can. Use a dental pick to remove it if possible. Fragments of the algae can spread though, so make sure to net any pieces that break loose. Yeah I know, it is boring as can be, but if you do it once surgically with a dental pick the problem goes away for good. If you can take the rock out, all the better.

Clean Up Crew- Emerald Crabs, urchins, sea hares, and large turbos.

Tip - Don't pass on frags with this stuff to other hobbyists, don't put one in your tank. This algae has become extremely common on traded/aquacultured frags. So my advice is every time you add a coral or a rock look for it from now on. It is easier to keep out of the tank then deal with it once inside. 

 

Lyngbya

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Often a reddish brown, Lyngbya spp. are a type of cyanobacteria. Even though it looks just like hair algae and is filamentous rather than slimy. It dislodges easily from the rock, has no discernible root or mat structure and grows fast. Lyngbya species seem to grow very fast in warmer tanks, and spread quickly once attached to a powerhead, suggesting they can replicate by fragmentation easily. Nevertheless aggressive manual removal over time can be effective.

Manual Removal -Toothbrush off the rock and glass capture floating mass in nets.

Clean Up Crew- Nerites, Ceriths, Chitons, Blue legs and Ragged Sea Hares all eat it as well as others

Tip - For the most part treat it as you would red slime algae type cyano.

 

Cladophoropsis, Green Wiry Algae

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Species in this genus, and related ones, cling to the rock, and spread from a runner. The branches do not get tall, and they are often found with hobbyist frags or on live rock.

Manual Removal - Difficult. Macros that have fragile runners and creep along the rock are the hardest to manually remove. Do the best you can. Get a dental pick and get it all the first time and be done with it.

Clean Up Crew- Rock Boring Urchins, Emerald Crabs, Turbos, and Sea Hares occasionally pick on it, but it dont seem particularly interested in it.

Starving it out - It seems to be particularly good at adapting to nutrient lulls, and it is unlikely that a small amount of the algae here and there will be starved out of your tank.

Fortunately these algae species tend to grow slowly, and aren't particularly common.

We distinguish this from Green Turf Algae by keeping this heading limited to green algae that creep along the rockwork, rather than grow up from it.

 

Cotton Candy Algae

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Algae under this heading usually appear as a light pink fuzz. Closer examination will show it is made up of many branches with even more branchlets. The plants are very small, lose form out of the water and sway in the current. Each plant forms from a single holdfast. Callithamnion species and the sporophyte stage of Asparagopsis taxiformis are usual suspects. The pictured specimen is quite good looking, they usually dont have such an aesthetic appeal, and are a dull red or reddish brown.

Manual Removal is easy if it hasn't taken hold in places your fingers won't fit. Scrape your thumb on the surface it is attached too while holding the algae like a pencil as you remove it. This helps you get the small holdfast.

Clean Up Crew members include urchins, sea hares, large turbos, emerald crabs and most hermit crabs.

This algae isn't particularly common, but has the ability to grow rapidly from fragments.

 

Red Bubble Algae, Botryocladia

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Red Bubble Algae is one of the Botryocladia species, (probably skottsbergeii or pyriformis) . Some of the Botryocladia species, like Botryocladia occidentalis, are desirable. The main difference between an invasive species of Botryocladia and a desirable one is how it grows. Desirable species grow up from branches, and invasive species creep along the rock just leaving hard to remove bubbles. Some are in between both in risk and branch development.

Manual Removal - Don't be clumsy and spread this one. Get em small, cover them with a baster, scrape the baster along the rock, when the bubble comes off release the plunger and suck it up. Discard and repeat. If you have a lot to do, by the time you are done you will be ready to add new mixed water to complete the water change. Be aggressive with your manual removal.

Clean Up Crew- Emerald and Ruby Mithrax Crabs will eat it, as well some Rabbitfish. Juvenile Mithrax are generally best for the task, the smaller the better.

 

Dictyota

dictyota 300x400Brown algae that has forked branches which may have an iridescent blue hue. There are tons of species of Dictyota and w/out a microscope the best you can get it down to is a handful of different species. If it is a brown algae, with forked branches, and isn't rigid; it is probably a Dictyota sp. Some species of Dictyota are desirable, you will be able to recognize them as they grow as one plant that branches out from one distinct holdfast. Removal would be very simple. Nuisance species of Dictyota, (pretty much all the iridescent species.) stay shorter and creep along the rock. Their branches form straight from the rock, and there is no trunk like feature to the algae, or easily discernible holdfast.

Manual Removal -Only large established patches are difficult to remove, treat incoming liverock with it in the dark, or in a separate tank before adding it to the display. If it does make it in your display dont allow it to spread, it is easy to control if it stays managed early on. Take a dental pick and scrape off every inch of holdfast you can. Get it all the first time and be done with it. At the least get it down to its minimum so the cleaners can polish it off.

Clean Up Crew- Emerald Crabs, Sea Hares, some Turbos, Chitons, Limpets, Tangs, and Urchins will eat it. Longnose Decorator Crabs will devour it, they go crazy for Dictyota.

Starving it out - While it seems to be able to survive nutrient lulls, its growth is much easier to check than cyanobacteria and many of the species we have looked at in this guide so far. Competing macroalgae can help slow the growth of Dictyota, and many can outpace its absorption of nutrients. Members of theChaetomorpha and Caulerpa family are particularly effective, once established.

Many species of Dictyota that fall under this heading are epiphytes, and can grow on other organisms, including Halimeda, and even some corals, or portions of the coral's base.

 

Chondria

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These and related species look like translucent red plants with cylindrical and irregular branching. They may stick to the rocks like Chondria repens, or they can brachout like the bushier Chondria minutula. The important thing in identification is look how the "branches" have smaller branchlets, usually ending in a pit.

Manual Removal - Fairly easy. While macros that have fragile runners and creep along the rock are the hardest to manually remove, this macro tends to peel better than most. Get the holdfast and attempt to peel it off the infected surface, if you miss any go back and polish it off with the tweezers or a dental pick.

Clean Up Crew - Just manually remove. If it is a too much of it, then emerald crabs, larger hermits, urchins, sea hares, turbos and other cleaning crew members with significant cutting power.

 

Caulerpa Racemosa, Grape Caulerpa

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Caulerpa racemosa has perhaps single handedly given Caulerpa spp. a bad name. Highly variable, it can be generally described as a grape like plant that grows up from a runner, (or root system). While other species of caulerpa may appear different, their treatment is generally the same:

Manual Removal -If you are going to manually remove it, use a dental pick to make sure you get every last bit of runner removed. The thicker the runner on your variation of caulerpa the easier this will be.

Clean Up Crew- Emerald Crabs, Sea Hares, Tangs, Angels, Urchins, some Turbos, Chitons, Limpets, and the Longnose Decorator Crab will all eat it this and other species of Caulerpa.

Why it happened - You didn't quarantine, and you have available nutrients for it. Try to keep it out of your tank, and if it happens to make its way in anyway try to get it out before it can spread.


Starving it out - Use a phosban reactor or a macro like chaeto to take down phosphate. If you have a nitrate problem too, you can add more live rock or rubble to the tank, do some more wcs, add macro, add dsb, etc...

Caulerpa racemosa in all its forms is invasive. Its runner is too fragile to practically prune and it can be a frustrating problem. If you like the look of grape caulerpa, try Caulerpa cupressoides var. lycopodium. It carries the same risks as other caulerpas, but its strong sturdy holdfast makes pruning easy.

 

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All for now, I will keep getting at it when I get some more picture permissions. Feel free to help me out by sending pics of pest algae.

I owe the authors of every photo a credit, I didn't take a single picture. They were all given by the members on this and other hobbyist forums on the internet. I didn't ask the authors for permission to use their name or likeness in this post, only the right to the image so names have been excluded. I would prefer to credit them, and will get around to asking permission.

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