Can I kill off blue-green algae with JBL Algol?
Blue-green algae, that is quite a complicated matter.
As is generally known, blue-green algae are bacteria. They photosynthesise, just like plants. Blue-green algae are among the oldest organisms in the world. They would have been extinct a long time ago if they didn’t have a few special properties. For example, they influence the medium on which they colonise to their own advantage, i.e. manipulate the environmental parameters (which only very few organisms are able to do). This property has secured their survival. In their natural surroundings, blue-green algae are absolute niche inhabitants, which are always inferior to other organisms in competition.
Blue-green algae need light and nutrients, just like plants.
Blue-green algae, though, also need a substrate for colonisation to grown on. They are inferior to "normal" biofilms both in nature and in an aquarium and can only spread if the “normal” biofilm has been destroyed and has partially died off. Then they colonise quickly and consequently grow over the “normal” biofilm. As they change the water parameters under their own film, the normal biofilm dies off expansively, and the blue-green algae aquarium is born.
Algaecides are only effective against blue algae to a certain degree.
The only effective method currently known is deprivation of light, meaning full deprivation, to which they exhibit a very sensitive reaction.