One of the most common types of algae that shows up in saltwater tanks is actually not an algae at all. It’s a bacteria called “cyanobacteria” or “cyano” for short.

You’ll know if you have cyano as it looks like red velvet on your rocks, glass or sand

You’ve probably encountered cyano before and you probably did what most hobbyist do which is to suck it out of their tanks or to increase the flow across the cyano outbreak.

Cyano problem solved right?!

I hate to the bearer of bad news, but sucking out cyano or increasing your flow won’t do much (if anything) for eradicating it in your tank.

Why do I say that?

For a couple of reasons:

1. It is hard to beat evolution. Cyano has been around for billions of years. Needless to say, it is resilient stuff. It knows how to survive in water, out of water and everywhere in between. Which brings me to my next point…
2. Cyano grows because it has the nutrients it needs. If you remove the cyano without getting rid of the nutrients, then it will come back. The same is true if you increase the flow of water across the cyano outbreak – it is going to come back. Sure you can keep sucking it out of your tank, but that gets old fast and you aren’t solving the problem. Ask yourself, what would you rather do? Pump out a flooding basement without plugging the hole where water is rushing in, or plug the water hole, then pump out the flooded basement?

Hopefully you chose to plug the leak, then pump out the basement.

The key to making sure cyano doesn’t come back is to attack the nutrients in your tank. Simply removing the cyano or increasing the flow across it is doing nothing more than avoiding a problem in hopes of a temporary gain which never works out in the end.

Coming tomorrow: your one stop shop for solving your cyano and other algae problems