Do I need to add organics?
KH
PH
Overview of what people try.
Black out used to be a very popular remedy, but I have no idea to what degree such a treatment harms coral. It is still used. Sometimes it works well.
There is the Chemiclean treatment. If directions are followed religiously, the treatment seems to be the most successful. Whether the cyanobacteria reappears depends on unknown factors like cyanobacteria species and conditions in the aquarium. There are some who consider using Chemiclean as a cop out of sorts.
The natural approach strives to alter the aquarium environment to discourage cyanobacteria growth. Increasing water flow where the cyanobacteria is growing, vacuuming up or blowing off the mats, reduced feeding, etc. all in an attempt to reduce organics in the system and make the surfaces inhospitable to cyanobacteria growth. Sometimes WasteAway is is used. This is the slow approach and whether the cyanobacteria recede because of the actions taken or it would have stopped if nothing was done is unknown.
Finally, there is help the competing organisms. In this narrative, low nitrate and maybe low phosphate starved the competing organisms that keep cyanobacteria in check. This is a relatively new narrative that has gained popularity. The idea is to tweak the nitrate and phosphate levels up to help the competing organisms starve out cyanobacteria. Like the natural approach, it is a slow, long term method in which you will never know whether doing nothing would have worked just as well.
The typical approach probably involves trying many methods at the same time. This is OK because none do any harm, except maybe the black out remedy, and it makes you feel better that you are doing something. No one can predict when cyanobacteria will start to grow or why. This can lead to frustration when using the above methods.
