Testing and adjusting your pool's pH level is an essential part of swimming pool winterization. Here's why it matters and how to do it.

That's why the CDC and others urge pool owners and managers to test chlorine and pH levels all the time — they can change day to day based on pool usage.

The Olympic diving pool in Rio caused a buzz when its water turned an eye-catching green colour earlier this week. Here's a scientific look at the explanations offered by Olympic officials.