The Wrongman's Fix It Guide: Section 16, Chapter 1, Paragraph 35

Algae growing in your swimming pool? Don't use chlorine, use bromine mixed with iodine. Like all typical autotrophic organisms, algae fucking hates iodine and the bromine vapors are corrosive and toxic. So, basically, you can kick back and relax as that means the bromine will do all the hard work. Like my Mom used to say: "There's no need to scrub the algae clean as the bromine brings a crystal sheen." HOLY SHIT THAT RHYMES.