The invention relates to an
algaecide. The
algaecide which can be used for effectively removing
algae and precipitating alga bodies contains
chitosan,
fly ash autoclaved
brick powder and allelopathic chemicals of
gallic acid, nonoic acid or N-phenyl-
naphthylamine, and is obtained by dissolving a certain amount of
chitosan by using
hydrochloric acid, then adding the
fly ash autoclaved
brick powder of 40-200 meshes, and then adding the
dimethyl sulfoxide assisted dissolved allelopathic chemicals of
gallic acid, nonoic acid, N-phenyl-1-
naphthylamine or N-phenyl-2-
naphthylamine. The
chitosan and the
fly ash autoclaved
brick powder used in the
algaecide provided by the invention are nontoxic, the allelopathic chemicals of
gallic acid, nonoic acid and the like belong to
plant secondary metabolism products, can be degraded easily in a
water body and cannot cause secondary
pollution, and although the diluted HCl solution is used for dissolving chitosan, great changes of the pH value of the
water body are not caused in a dosage range. The algaecide provided by the invention can be used for removing the
algae effectively and ensuring that the alga bodies are sunk to the bottom of water, has a small influence on the environment and does not cause secondary
pollution, the
water body is clear, and the beautiful outlook of the water body is not influenced, so that the algaecide is suitable for removing the
algae from a small landscape water body taking blue algae as a dominant species.