Certified Pool Operator Practice Test

It is commonly accepted to use 0.125 pounds of precoat per sq. ft. of surface area for DE filters. This ratio has been determined as the most effective amount for trapping debris and achieving optimal filtration. Answers B, C, and D are incorrect because they suggest using a higher amount of precoat, which can result in clogging and decreased effectiveness of the filter. Using a lower amount of precoat, such as 0.1 pounds per sq. ft. (not included as a choice), may not provide enough filtration and result in reduced water clarity. Therefore, it is important to use the recommended amount of 0.125 pounds per sq. ft. for optimal performance of DE filters.