Article in English: Get pH testing strips at your local pool store, big-box store, or order them online. Follow the product’s instructions, which are typically dipping the strip into the water and checking its color against the range listed on the product. Some pH test kits require you to fill a small tube with pool water and add drops which change color based on the pH. Record the pH level in a small notebook to track the change over time. The pH of your pool changes frequently due to many causes. This is why it's important to check often. Write the pH down in a notebook to track it as it changes over time. . Test strips change color when exposed to water. The color corresponds to the pH level. Match the color to the package and you’ll find the current pH level. The ideal pH level for a pool is between 7.4 and 7.8. Determine how many points you need to raise the pH. For example, the color of your test strip might show the yellow of a banana. According to your product, this means the pH level is 7.2. You’d want to raise the pH by a minimum of .2 and a maximum of .6.

Summary in Vietnamese:
Dùng que thử độ pH. Kiểm tra nồng độ hóa chất từ một đến hai lần một tuần. Duy trì độ pH ở mức từ 7.4 đến 7.8.