We don't have synonyms for red tide yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are red tape, red pine and lee tide.
(n) :
An algal bloom of sufficient quantity to cause discoloration (often red) in a body of water; red tides can potentially cause irritation or death to exposed creatures.
(n) :
An algal bloom of sufficient quantity to cause discoloration (often red) in a body of water; red tides can potentially cause irritation or death to exposed creatures.