ChimneyRx Safer Brick & Masonry Fireplace Cleaner - 1 Gallon Cleans Rust, Smoke Stains, Efflorescence, & Algae Stains from Masonry Surfaces Patented Chemistry Virtually Eliminates Toxic Fumes & Potential Acid Burns Normally Associated with Muriatic Acid Equally Effective, But Safer Than Muriatic Acid 1 Gallon Concentrate Makes up to 5 Gallons of Cleaning Solution Low Odor & Low VOCs