Blanketweed Control

Blanket weed (Spirogyra adnate) is one of the most prolific aquatic weeds known to amateur and professional pond-keepers in the U.K. In America it is called Long String Algae. This description is pretty accurate because in effect Spirogyra is not a plant but a filamentous algae. There are several other aquatic weeds which are also filamentous algae and the most prevalent of these are Cladophera, Rhizoclonium, Vaucheria and Ulothrix (Ulothrix is a Chlorphyte like Spirogyra and looks very similar).

Blanket Weed is a long thin filamentous alga, which like Ulothrix thrives in ornamental ponds. As can be seen from the microscopic observation, the cells of Spirogyra are characterised by helical shaped chloroplasts which give the weed the pronounced green commonly associated with Blanket Weed. Its growth is increased by bright sunlight and shallow fast running water so that it will be found in water-falls and unshaded pond areas. In ornamental ponds which tend be stocked with fish, the tendency to overfeed causes additional fish excrement which contains nutrients favoured by Blanket Weed particularly nitrates and dissolved ammonia. This means that apart from normal growth by photosynthesis the weed will grow even faster.