Red spot algae is a type of red algae (rhodophyta) that forms bright reddish brown circles on the glass and red coatings on the leaves of plants. It clings very tenaciously to everything. It can take determined scrubbing to remove it. It is relatively slow growing. It generally comes with high nitrates or high iron.
Red Algae in the Aquarium Red Algae in the Aquarium Source : Aquariumscience.org – David Bogert
David Bogert The author, David Bogert, is a certified chemist, something that is only useful in the sections on chemicals such as conditioners and fertilizers. He has about 43 patents, mostly in the medical device field, which only helps with some DIY designs. But he also spent much of his life as a scientific researcher working on literature research, data analysis, statistics, and a little-understood field called "experimental design." This experience is very applicable to ALL fishkeeping science. The author has been keeping all kinds of aquariums and all kinds of fish for over 54 years. He currently has ten large and many small aquariums. But note that he is not an "expert" in all aspects of aquarium keeping. The ecology of an aquarium is far too complex for anyone to be a true "expert" in all the different aspects. One can only search the journals and books for relevant research in each individual subject.