Mainstays 6-Way Pool, Hot Tub & Spa Test Strips. Keep your water clean, healthy, and enjoyable with our 6-in-1 test strips for pools and spas. Our strips test water for hardness, chlorine, free chlorine, pH, cyanuric acid, and alkalinity. Simply dip the pool strips into the water, get your results within seconds and adjust your water accordingly. Each bottle contains 50 test strips. If used weekly, this test kit will last up to 1 year.