Yes that is Cyanobacteria.
While ther is no conclusive evidence there are several factors that seem to contribute to the bloom of cyano. There are some areas that need to be looked at, too much proteins in the water column, lack of water flow, the presence of phosphates and nitrates and high intensity poor quality lighting. Even though maracyn will take care of it if the above is not looked at there is a good chance that it could come back.