AquaChek Silver 7-in-1 is ideal for customers who want a more complete analysis of their pool or spa water. Get 7 important test results in just one dip! Dip an AquaChek Select strip in your pool or spa water for one second and remove it immediately. You get test results in seconds! To keep you pool water clean and healthy, test the water at two ends or sides of the pool a minimum of twice a week! If used in a spa we recommend testing it before and after each use. Pool and Spa testing is also advised after heavy swimmer use (i.e party), after animals have been in the pool, after a heavy rain, after fertilizing, etc.