What is the primary purpose of pool filters?

The primary purpose of pool filters is to remove debris and contaminants from the water. Filters play a critical role in maintaining water clarity and sanitation in a swimming pool. By trapping particles such as dirt, leaves, algae, and microorganisms, filters ensure that the water remains clean and safe for swimmers. This process also helps prevent the buildup of harmful bacteria and creates a more pleasant swimming environment.

While circulating water is an important function of pool systems, the specific role of the filter is to physically remove impurities. Heating the water and changing pool lighting serve entirely different purposes and do not contribute to the filtration process. Thus, option C accurately reflects the fundamental task that pool filters are designed to accomplish.