Coralline Algae – Love It Or Hate It

Coralline algae (which is a red algae with a calcerous based skeleton), in my opinion adds colour to the aquarium. Once it starts to cover the live rock numerous shades of red add a certain different aspect to the rocks. You have probably seen aquariums like this either in person or in pictures.

Coralline on the glass though – it is a different opinion – at least for me it is.

I don’t mind it on the live rock or even the pipework but I have a distate for it being on the glass. As soon as I spot it on the glass I attempt to remove it by either a scraper or if it is a tricky little blighter I use a razor blade.

I suppose this bring me onto another aspect – where does it come from?

[tag-tec]Coralline algae[/tag-tec], which is not to be confused with red slime algae, normally starts to grow in an aquarium when live rock is introduced – either as a filtration medium or via a coral attached to a piece of live rock. Once the aquarium becomes stable and the correct water quality maintained the coralline quickly starts to spread.

There are lots of different colours which can be seen, however I have noticed that the colour is normally darker towards the bottom of the tank or in areas where there is less light. Normally coralline actively starts to grow when there is sufficient calcium present in the water. You do however, need to monitor the calcium levels to ensure that they do not drop below an acceptable limit and if possible attempt to keep it stable.

I have a good coverage of coralline in my aquarium. There was not a lot when first set up but over time it has grown but I personally believe that because I scrape it from the glass that the scrapings float along in the water column and where they land they attach and grow. I have also noticed that where there is coralline present on the live rock it appears to prevent other algae from growing. Why I am not sure but it definately does.

Therefore if you have an aquarium which is low in [tag-tec]coralline[/tag-tec] then why not scrape some coralline from another area and let it float free in the water column. You never know over time it may spread. Another good method is to introduce some small pieces of live rock from an established aquarium which are covered in coralline algae and place them in crevices around your live rock structures.

I do wonder if coralline algae covering the live rock will prevent or reduce the functionality of the live rock. I don’t believe that it does. My reason for this is that live rock is basically full of tiny holes and burrows which are smaller than the eye can see. If we were to remove some live rock and examine it closely under a microscope then I believe that there will be lots of minute little holes and crevices covering the surface allowing the water to enter the live rock where it is filtered.

To me coralline algae can make an aquarium visually more atractive and I suppose that this is what is good about this hobby – everyone has their own belief as to what looks nice and what does not. I don’t like it on the glass but someone, somewhere in the world will find it exceptionally attractive.


Coralline Algae – Love It Or Hate It
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3 Comments
  1. I’m with you … I don’t dig how coralline algae looks on glass. On live rock is cool; mixed feelings about it covering the back wall. Although I am told that it is a good sign when you begin seeing it grow. I have some on the live rock in our tank, but not on the walls yet. The marketing department here at Marine Depot has had our 24-gallon AquaPod up and running since about mid-May … about 3 months. I will probably post some updated photos in our Flickr account this week. Check ’em out!

  2. I’ve allowed coraline algae to grow on my back glass, and if its there its obviously on rocks. The appearance is brilliant, real ‘reefy’. I clean it off the viewing glasses periodically. I try to give it the best environment with calcium addition and maintenance of alkalinity at just under 4.0 meq/l.
    But its all in the eye of the beholder.

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