Saltwater Aquarium Algae Types…An overview

I have heard this question at least a hundred times…. What kind of algae is this?

What we will discuss…

We are going to touch on several types of algae. There are hundreds of kinds and there is no way I could explain all of them on a page, it would take an entire site. I’ll touch on some of the most common types and some ways to control them. We will also talk about the saltwater aquarium algae bloom. This can strike no mater how old or well maintained an aquarium you have. I am trying to keep the algae in the order you will see them pop up in your tank. Again all aquariums are unique and there are no set rules.

This is not a scientific site so I will be mixing Latin and common names and all info and circumstances of course is dependent on your unique biological system. Again this is for the hobbyist.

Diatoms…the first strike20160325_205816[1]

The first “algae” marine hobbyist encounter is usually not an algae at all but cyanobacteria and diatoms. They are brown to reddish color and gathers on your rocks, glass, and free floats in your tank. The good news is that this usually clears up when you get the nutrients and phosphates under control. Once the tank finishes the nitrogen cycle and all of your levels come to normal and good algae takes the place of the diatoms. Manually remove it and water changes will clear it up quicker and “starve” your tank. You will here these 2 things over and over through this page. Also starving your tank is controlling your nutrients and not feeding your tank. Make sure you have good water flow and no dead zones and check phosphates and iron. Cyanobacteria grows faster in warmer water.



Green Film Algae…the reason for glass scrapers

This is the algae that covers your glass and gets on your rocks. It’s usually green and sometimes has some brown in it. This algae has no real form to it and generally dissolves when removed from water. There are several marine fauna feed on this including copepods, amphipods, and isopods. This algae is normal and in most cases is good and healthy in your tank and is the bottom of the food chain. When your nutrients and phosphates are high there can be a bloom of algae and that’s always a bad thing. Clean up is simple and most grazers will feed on it. This includes hermit crabs, chitons, turbo snails, and most other mollusks.  Manually remove by scraping glass and immediately doing a partial water change sucking up the floating debris. Do not get discouraged about this type of algae you will never rid your aquarium completely.



Green Hair AlgaeGreenHairAlgae

There are literally hundreds of different types of hair algae and true identification can only be done with a microscope. This algae characteristics are that is usually very soft and has no root structure. It breaks up easily  and looses it’s form when removed from water. Hermit crabs, and other crustaceans feed on most types of this algae. I personally keep Tangs for this purpose because they are reef friendly and will eat most types of algae. In addition if I am starving my reef tank I am not starving my fish in turn because they graze most of the time. Some people grow this algae in special algae filters for feed and filtration. Remove this stuff manually by rubbing your finger or thumb along the base and sucking up the loose algae. If it is in your substrate take your aquarium vacuum to it and suck it out. Maintaining the nutrient levels and partial water changes weekly should keep this algae under control.

Some Good Algae You Really Want…

Coralline Algae20160326_120621[1]

Believe it or not there are several algae that you really want in your marine system. The first is purple or coralline algae. This algae covers your live rock and is various colors of purple, pink, and red. It is beautiful and takes time and good water conditions to grow and maintain. there are products out there to promote the growth of this algae. You can also buy live rock with it already on it. If you do not have good water conditions and water flow you will not be able to keep nuisance algae from smothering it out.

algae up


  • Steve says:


    I have been trying to fight Diatoms in my 100litre Marine tank for months. Nothing I have done has got on top of it.

    Do you have any suggestions for really knocking it on the head! I have tried different light levels (led), different temps, salinity, etc… I really don’t feed a lot just a few pellets each to my fish.

    Hope you can help

    • Adam says:

      That is usually a nutrient problem. Newer aquariums also experience this at the end of the nitrogen cycle. I would also ask you how often you do water changes. I usually change around 15 percent a week. What type of filtration are you using? How much live rock and how deep is your substrate? In addition, you can make sure there are no dead spots in your tank. In that there are no places without current. Even if its gentle. Another issue could be over stocking. Fish waste adds nutrients that help diatoms flourish.

  • Josue Castillo says:

    Hi there. you have some really great stuff going on here with your site. It is very informative and for someone like me who isn’t at all an expert in this subject, it is also really easy to read and understand. I can not tell you how many I have gotten super lost when reading articles and posts about new subjects. Your site, however, is actually very good at keeping a reader caught up. I did notice a few grammar errors, but I think with a quick review you should be able to straighten them out with no problem. Well keep up the work and good luck.

    • Adam says:

      Thank you Josue for taking the time to stop by. I probably should have proof read it before posting. Usually I wait a day then read it and publish but was a little in a hurry. New things will be added as time goes on and we are considering opening a custom setup and maintenance service. Thanks again for stopping by and look forward to seeing you in the future

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