I had a minor out break of this but jumped on it as quick as it started.

The quick solution in my opinion...is Chemi-Clean!  Its a white powder in a small bottle with spoon included for doseing the tank.  Its truely a effective 24 to 36 hour cure for sure, but requires a 25% water change afterwards if memory serves me correct!  I have not had a problem since.

I do believe this is a bandaid on a cut throat though.

Sounds like you have a nutrient rich water problem.  This is purely speculation though.  I did feed very sparingly since.  I have added more live rock, more plants and added more crabs and havent had an out break since

Just food for thought....

I had a bad cyno out break, covered everything. I added activated carbon, every week and regularly cleaned out my filter floss every week. When I had my out break my skimmer wasn't even working. Just using carbon and clean filter floss in my sump helped alot. I also limited my light. Good luck. Nigel

When i had my first Cyano outbreak in my tank I thought I had read that cyano actually had algae in its cells.  Here is a rip from some webpage talking about cyano.  Seems it can create its own food.

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Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth.

Many Proterozoic oil deposits are attributed to the activity of cyanobacteria. They are also important providers of nitrogen fertilizer in the cultivation of rice and beans. The cyanobacteria have also been tremendously important in shaping the course of evolution and ecological change throughout earth's history. The oxygen atmosphere that we depend on was generated by numerous cyanobacteria during the Archaean and Proterozoic Eras. Before that time, the atmosphere had a very different chemistry, unsuitable for life as we know it today.

The other great contribution of the cyanobacteria is the origin of plants. The chloroplast with which plants make food for themselves is actually a cyanobacterium living within the plant's cells. Sometime in the late Proterozoic, or in the early Cambrian, cyanobacteria began to take up residence within certain eukaryote cells, making food for the eukaryote host in return for a home. This event is known as endosymbiosis, and is also the origin of the eukaryotic mitochondrion.

Because they are photosynthetic and aquatic, cyanobacteria are often called "blue-green algae". This name is convenient for talking about organisms in the water that make their own food, but does not reflect any relationship between the cyanobacteria and other organisms called algae. Cyanobacteria are relatives of the bacteria, not eukaryotes, and it is only the chloroplast in eukaryotic algae to which the cyanobacteria are related.

Determine what is feeding the cyanobacteria (source of excess nutrients) and stop it or remove it! Sometimes no feeding for five days and then feeding less will control it

Fish food, detritus hanging around, etc.

Insufficient consumption of nutrients in the RDP Sump will ALWAYS lead to algae growth in the main tank. (algae types, insufficient illumination, nutrient buildup, detritus buildup, if sand in the sump has never been exchanged with someone wanting live sand, etc. 

TPF has some abalone, yesterday they showed me is eating up their cyano! It's a neat looking mullusc too!

Keep trying Shane, I'm confident you'll get it under control.

Increased water flow will help alot and sand shifting stars will help move the sand around to help keep it from coming back...

Ryan

www.marine-aquatics.com

Have you tried increasing your water movement.  This will usually wipe it out.