Sentence 1: Jeff went downstairs to clean his saltwater fish tank. 
 Sentence 3: He used a scraper to loosen the algae 
 Sentence 4:  The fish hid in the decorative structures on the bottom of the tank 
 Sentence 5:  Jeff used a net to collect the algae and the water looked cleaner 
 Given Sentence 2: There was a lot of algae growing on the back of the tank.