Related Clues:

• Rust removers
• Biting — tart
• Substances low on the 49-Across
• Acetic, for one
• Word before rain or test
• __ test
• Sulfuric ___
• Pool supplies
• They're not basic things
• Nitric ___
• Etching stuff
• It's not basic
• Need for 41-Across
• Biological food processor
• Omega-3s, e.g