This page contains affiliate links.  All that means for you is that if you click on one of my links and make a purchase, I receive a small commission.  This helps me keep this content 100% free!  But rest assured, I only recommend products I know and trust! Happy Reefing!

The Beginner Guide To Nuisance Algae

Table of Contents

In the saltwater aquarium hobby, nuisance algae is really any type of algae (or bacteria) that grows quickly, takes over your tank, is difficult to remove, or is unhealthy for your livestock. Some types of nuisance algae merely look bad, while others can kill your livestock.

This post is a brief introduction to the most common types of nuisance algae you will come across as a beginner, how to get rid of them, and general guidelines on how to keep nuisance algae at bay.

I) What is Nuisance Algae

Any type of algae that tends to take over a tank, covering rock-work and corals, and being difficult to remove.

For example, diatoms could be considered nuisance algae because they are unsightly, but then again they are somewhat easy to remove and usually show up as a part of your tank cycling.

Two clear examples of nuisance algae in the marine aquarium would be hair algae and bubble algae.  Both these types grow quickly, are not readily eaten by average cleanup crews, and can easily take over an entire aquascape.

Bubble Algae, © Marine Depot
Hair Algae, © Marine Depot

There is no hard and fast list of what makes up nuisance algae, but if it’s an algae that’s a pain in your side, you can rightly call it a nuisance!

Nuisance algae can be removed manually, by using certain livestock, by using certain chemical treatments, by reducing phosphates, by installing a refugium, etc.  You get the idea!

The best cure for nuisance algae is prevention.  Properly quarantining your livestock can help you spot problem algae before reaching your display tank.

1) Where Does Nuisance Algae Come From?

There are so many different ways that nuisance algae can be introduced to your aquarium:

All it takes is a single spore and bam, you’ve got nuisance algae.

It is nearly impossible to completely eliminate nuisance algae from your tank, but there are things you can do to make it less likely.  Properly inspecting all new livestock, using a quarantine tank, and manual removal will all help.

Best to be proactive and take care of issues the instant they arrive.

1) What Causes Nuisance Algae to Grow?

There are two factors that cause nuisance algae growth:

a) Light

Just like plants above the water line, algae primarily relies on photosynthesis for their food.

When you are planning the lighting cycle for your saltwater tank, keep in mind that in nature, most tropical fish average somewhere around 10-12 hours of sunlight each day, and during that time period, only 4-5 hours of the day is PAR intensive light.  So if you are running your aquarium lights for 16 hours a day, expect lots of algae growth.

Personally, I run my lights for 12 hours each day, with a 4-5 hour photo period of intense lighting.

It is also important to think of how the color spectrum contributes to nuisance algae growth.  If you search up “grow lights” on Amazon, you will likely find LED’s that contain a lot of red and purple, with some blue, orange, and white mixed in.  So the moral of the story is to keep the red spectrum to a minimum when planning your lighting schedule.

b) Nutrient Levels

But lighting is only half the issue.  Nuisance algae will thrive in nutrient rich environments, especially with high phosphates and nitrates.  Overfeeding and overstocking your tank are two of the biggest culprits here.

Using a test kit frequently will help determine if your nutrient levels are high.  Lowering the quantity and frequency of feeding will help, but also the type of food matters.  For example, pellet foods are super dense, nutrient rich food sources, and if they go uneaten or fall to the bottom of your tank, can break down into phosphates and cause your nitrates to rise.

Whereas frozen food is typically less nutrient dense, and, especially if you rinse it first, can provide the sustenance for your livestock while not contributing to algae growth.

You can also run an over-powered protein skimmer, and even consider adding a macro algae refugium to combat those nutrient levels.

II) How to Get Rid of Nuisance Algae

It can be daunting when you first experience nuisance algae.  It may be covering up all of your live rock, maybe even encroaching on your corals.  While you need to contain an outbreak when it occurs, there are 8 general husbandry issues that will give you a greater chance of success in the long run.

1) Lighting

Less is best.  Most algae especially enjoy red/purple lights, so keeping that spectrum to a minimum will help.

Also, there is a huge difference between a 12 hour day and a 16 hour day when it comes to running your lights.  

Not only that, but there is a ginormous difference between 50% intensity and 100% intensity.

So, if you are having nuisance algae problems, cut back on the red spectrum, the length of your lighting cycle, and the intensity.  

Try to run a lighting program for 10 hours each day, with a four hour photo period of relatively high intensity lighting, and a two hour ramp up/down, with a bit of moonlight at sunrise and sunset.  It will help reduce algae growth, I promise!

2) Clean Up Crew (CUC)

We have an entire Beginner Guide to Clean Up Crews, so check it out!

Every member of a clean up crew is good at tidying up something, but no member of the clean up crew can handle it all.  And, there are just some types of algae that nobody seems to want to eat!

For example, while many websites will claim that hermit crabs and various types of fish will eat hair algae, I don’t think I’ve ever met one that did!

And some clean up crew members come with warnings because they will eat your corals or kill other fish!

So what is a beginner to do in this daunting world?  Here is my recommendation.

Start with snails.  Get snails that will eat algae (Turbo, Trochus, Astrea) and get snails that will eat detritus (Cerith, Nassarius).  And then expand out from there.  But at least you’ll have good start with snails!

But don’t be fooled into thinking that the perfect clean up crew will solve your algae problems.  It won’t, and you will still have to manually remove nuisance algae from time to time.

3) Manual Removal

While manual removal is a huge pain the butt, sometimes it is your best offense and defense.  If you can spot nuisance algae at the beginning, it is oftentimes localized to either a single snail shell or piece of live rock.  As long as you are careful, you can pick it off and voila, the outbreak has been averted.

I’ve found manual removal especially helpful with cyanobacteria (not algae, but looks like it), as well as bubble algae.  There is a trick to removal though.

If you just stick your hand in the tank and try to pick the nuisance algae off, it will likely spread around the tank and find a new home.  So best case scenario is to remove the offending piece of live rock/livestock and remove the algae in a separate bucket.

But if that’s not possible, the second best thing is to get a friend’s help.  Have your friend hold your gravel vacuum right over the top of the algae while you pick it clean.  That way, as you release the algae, most of it will get sucked into the siphon and out of your tank.

4) Refugiums

If your space and budget allow, adding a refugium can help reduce your nitrates and phosphates naturally.

Here’s how it works: algae thrives when given a lot of light and a lot of nutrients in the water column. When there are less nutrients to feed on, it either grows more slowly or starts to shrink (wishful thinking I know!).

You put macroalgae (big algae) into the refugium, add a light, and this good algae will start to consume those phosphates and nitrates alongside your nuisance algae.  Over time, the macroalgae will out-compete the nuisance algae and consume more nutrients, thus reducing the total nutrients available for the more pesky forms of algae.

So whether you have a sump or purchase a HOB, a refugium can be a big help in combating high nutrients levels.

CPR Hang On The Back Refugium

5) Skimmers

Protein skimmers are by no means necessary to have a successful reef tank.  I currently have a 24-gallon saltwater aquarium with a couple fish and lots of corals, and the only filtration I run is live rock and a sponge.

That being said, high nutrient systems (either because of too many fish or too much food) will greatly benefit from a skimmer.  A skimmer will remove those very fine solids that make it past your filter socks.

So if your nitrates are running high, consider adding a protein skimmer into the mix.

I would always recommend getting a skimmer that is rated for a bigger tank, that way you are sure to get the most skimming power possible.

6) RO/DI Water

Any seasoned hobbyists knows that you don’t use tap water to make saltwater.  There can be chlorine, chloramines, heavy metals, phosphates, and many other elements that you don’t want in your tank.

So if you are having nuisance algae problems and are using tap water or well water, make the switch to either RO/DI water or distilled water.

Marine Depot RO/DI Filter
RO/DI Filter

7) Chemicals

While definitely not my preferred method, I will admit that sometimes I resort to chemicals to help fight nuisance algae.

But here is the rub: there are few options out there for a very small number of algae.  In fact, there are only a small handful I would even recommend, and with those there would be a lot of warnings.

For example, I’ve used ChemiClean many times with great success.  ChemiClean is an antibiotic that treats cyanobacteria (not algae, but similar in appearance).  But if you are not careful, using ChemiClean can consume a lot of oxygen in your tank and starve your livestock.

I’ve also used hydrogen peroxide with some success, but rarely in the aquarium itself, because even a small amount can destroy the fleshy polyps of your corals.

I’ve heard good things about Flux Rx to fight bryopsis and hair algae, but I’ve never personally used it.

8) Media & Reactors

Fist let’s talk about media.  You don’t need to purchase a reactor, but rather you can place media in fine mesh bags and place the bags in a high flow area of your tank.  Here is a list of media I recommend to help beginners fight high nutrients:

Pretty much all of the medias above can be placed in a simple mesh bag like this one below.

But all of the medias (except ceramic and Poly-Filter), will work more effectively when placed into a reactor.  Why you may ask?

Because a reactor has a pump attached to it with sucks in aquarium water, forces it to interact with the media inside, and then sends the clean water back into the water column.  It is a form of active filtration, whereas relying on a filter bag is passive and less effective.

Here is my favorite reactor/pump combo:

III) Most Common Types of Nuisance Algae

Let me reiterate, this is a beginner guide!  There are so many more in depth guides out there, but I wanted to make something easy to understand with the most common types of nuisance algae so that a beginner could benefit immediately without having to search the internet for hours!

If you don’t see your type of nuisance algae here, just type in “saltwater nuisance algae guide” into Google, and you’ll find quite a bit more information.

1) Diatoms

  • Description– You will get diatoms, I promise you!  Diatoms are almost alway present in new aquariums, especially during the nitrogen cycle and for several months thereafter.  They are nothing to worry about, even though they are brown, unsightly, and can cover your glass, substrate, and live rock!
  • Methods of Removal– manual removal is the easiest, as it can be easily scraped off the glass or acrylic tank.  You can gravel vac your sandbed, and use a brush to gently scrub your live rock. But honestly, I wouldn’t worry about cleaning the sandbed or liverock, as diatoms typically go away on there own.
  • Best CUC Options– Algae eating snails such as Turbo, Trochus, Astrea, Nerites will help keep the glass clean.  Ceriths, Nassarius Snails, and Conches will help keep the sandbed stirred up.

2) Film Algae

Film Algae, © Marine Depot
  • Description– Usually green, it is the algae that covers your glass, obscuring your view of the livestock within!  Probably the most common type of algae in saltwater aquariums, there is nothing you can do to completely stop it from coming.  I clean film algae off my glass tanks every 3-4 days. There is soft film algae which can be removed with a felt pad, and hard film algae which requires a stainless steel blade or box cutter blade.
  • Methods of Removal– Manual removal is the best method.  I recommend buying the Flipper magnetic algae scraper.  You can use the soft felt side for the easy to remove film algae, and as the hard encrusting algae grows, you can just “flip” it around and use the stainless steel (or plastic for acrylic tanks) side.
  • Best CUC Options– Algae eating snails will help reduce the amount of manual removal you have to do.  I’d recommend Turbo snails, Trochus, Astrea, or Nerite snails.

3) Hair Algae

  • Description– Also known as GHA or Green Hair Algae.  There is really no great definition, as hobbyists use this term for algae of a hundred or more different species!  But like this picture, hair algae clumps together and forms long hair-like structures.  It is a super pesky algae that can easily take over an entire tank, covering your corals and live rock.
  • Methods of Removal– If you spot any green hair algae, remove it immediately.  If you can pull the piece of live rock out, do that.  Otherwise use a gravel vacuum and your hands to remove as much as possible.  Cut back on your lighting length and intensity if possible, and reduce your nutrients using the methods in section II.  It will quickly spread to your entire tank if not dealt with promptly.
  • Best CUC Options– There really aren’t many CUC members that can contain a GHA outbreak, but I often see these recommendations: Hermit Crabs and Emerald Crabs, but I’ve never had much luck with anything other than manual removal.

4) Bubble Algae

Bubble Algae, © Marine Depot
  • Description– Just like it sounds, Bubble Algae forms tight groups of small bubbles.  It can spread quickly, so prevention is your best line of defense.
  • Methods of Removal– Prevention is key.  Inspect all new snails, live rock, and stony corals and remove any bubble algae.  If it does appear in your tank, be careful to not just try to scrape it off, as the bubbles will detach, float around, and find a new home in your tank.  It is best to remove the piece of live rock from your tank before removal, or use a gravel vacuum or turkey baster to make sure not to spread this pesky algae.
  • Best CUC Options– Emerald crabs are your best bet for removal, but beware, some emerald crabs have been known to nip and feed on corals.

5) Turf Algae

© My First Fish Tank
  • Description– Again, hobbyists use this term to describe hundreds of different species.  I think of turf algae as any sort of dense clumping algae that either forms dense mats that can be peeled off, or that sprouts directly out of the rock. In this pictures you can see the dense clumps of turf algae, and some hair algae near the bottom.
  • Methods of Removal– This type of algae can be quite tricky to get rid of, especially the type that seems to sprout directly out of the rock.  If you can remove the rock, do so, manually remove as much as possible, and treat affected areas with hydrogen peroxide.  If you can’t remove the rock, just keep on top of manual removal.
  • Best CUC Options– I’ve never had anything seem to work, but oftentimes Emerald Crabs and Sea Urchins are recommended.

5) Cyanobacteria (not algae)

  • Description– Also called blue/green algae or Red Slime Algae, this bacteria can be challenging to remove.  It has always appeared as a deep red color in my tanks, but can also be green/blue in color.  While not dangerous to your livestock, it is unsightly.  Excess lighting, high nutrients, and low flow all contribute to its growth.  
  • Methods of Removal– I would only recommend using ChemiClean as a last resort.  Try increasing the flow in your tank, eliminating any dead spots.  Lower your light length and intensity.  Use a vacuum to manually remove as much as possible, and a bristle brush to scrub the live rock.  Make sure to lower your phosphates especially, either through water changes or by using some sort of GFO. If all of that fails, try ChemiClean, but be sure to follow the directions closely or you can deplete all of the oxygen in your tank and kill the livestock.
  • Best CUC Options– Honestly, nothing will really help.  Nobody seems to eat it.

7) Bryopsis

By Hervey, A. B. -, Public Domain,
  • Description– So sorry but I could not find a good copyright free picture to use!  But this will do!  I’ve never had bryopsis in my tank, but it has a distinct structure, sort of like a little pine tree or fern.
  • Methods of Removal– Well, you can either manually remove it or use a product like Flux RX.  Hobbyists hate this algae because of how challenging it is to remove.  If possible, pull the live rock out of the tank before trying to remove this algae.  If all else fails, you can try Flux RX, but be sure to follow the directions carefully. You can also try to starve it out by reducing phosphates, nitrates, and lights, but this will take time.
  • Best CUC Options– Good luck here!  One of the reasons this algae is such a nuisance is because clean up crews rarely have much effect.  There is really nothing I’d recommend, but you could try Emerald Crabs,

8) Dinoflagellates

dinoflagellate algae clumped together on a white sandbed. Light brown in color with air bubbles attached to the end
Dinoflagellates, © Marine Depot
  • Description– It looks like gravity defying brown snot with an air bubble attached to the end.  You will know you have Dinos if your snails/crabs start to mysteriously die.  Dinos are toxic to invertebrates, and dreaded in the hobby.
  • Methods of Removal– They can be a real challenge to remove and I’ve struggled with them myself over the years.  Adding a UV sterilizer can certainly help.  Unlike other algae, it is believed that Dinos thrive in low nutrient environments where nitrate and phosphates are at zero.  So the first step is to increase your phosphate and nitrates to anything above zero.  Then recolonize your tank with good bacteria.  I like either Dr. Tim’s or Brightwell MicroBacter 7.  Then manually remove as much as possible every day. This is not a quick process so just keep at it.  It may take many weeks. 
  • Best CUC Options– Nothing. Dinos are poisonous to inverts.