I believe the methylene blue is more toxic to your beneficial bacteria than the green.
All treatments are basically liquid metal salts, and dyes that enter the cell(s), cause the infectious parasite, and any other bacteria they come in contact with implode (lyse( ie lysol))
Some such as salt (NaCl) or eosom salts are almost non toxic to most higher organisms in moderation, some are more toxic to simpler organisms in varying degrees, such as methylene blue.