If I were to sit down and catalog all the different types of nuisance algae, you wouldn’t hear from me for months. There are countless types of algae that can show up in a saltwater tank and every week I get a picture from someone wanting me to identify some strange new algae growth.

Despite all the different types of nuisance algae, there is one type of algae that you’ll likely mistake for a nuisance when in realty it is perfectly friendly. That algae is called “coraline algae”. (If you already knew this fact, scroll to the bottom of this post)

Coraline algae is a calciferous algae meaning it uses calcium in your tank’s water to grow. You can easily identify coraline algae as it is usually pink, purple or red in color (see the picture on the left) and encrusts over just about anything in your tank – rocks, pumps, glass, overflow boxes, etc. The only place I haven’t seen coraline algae grow is on a fish.

If you see coraline algae in your tank, don’t freak out because it isn’t a bad thing. A nice covering of coraline algae can conceal unsightly items in your tank like glue or zip ties holding rock work together. Also, the presence of coraline algae usually means your tank’s parameters are in check and that your tank is maturing.

Some saltwater tank hobbyists are so bonkers for coraline algae that they’ll do anything to get some coraline in their tanks. One person asked me to overnight ship coraline algae shavings to Asia! (See what I mean by hobbyists going bonkers?)

Of course there are plenty of hobbyists that detest coraline algae and scrape it off as soon as they see it show up in their tank. I don’t know why they hate it so much when it isn’t a nuisance and as the saying goes, “different strokes for different folks”.

You can choose to like or dislike coraline algae, but it certainly isn’t a “nuisance algae” in the sense that it can overtake your tank and kill corals. Strike coraline algae from your  nuisance algae list.

If you can’t get coraline algae to grow in your tank, make sure you read this post (For those of you that already knew coraline algae is a good thing, that link is for you too)

Coming tomorrow to your inbox: learning how to recognize when your tank is trying to tell you something.