ebb and flow vs low tide

ebb and flow

noun
  • The flowing out and in of the tide. 

  • A large flowing out and in. 

verb
  • To alternately ebb and flow. 

low tide

noun
  • The tide at its lowest level for a particular tidal cycle at a certain place. 

  • The time of day when the sea has receded to its lowest level. 

How often have the words ebb and flow and low tide occurred in a corpus of books? (source: Google Ngram Viewer )