Leisure Time Spa Chemicals Chlorine Test Strips are easy-to-read strips that test spa water pH, total alkalinity, calcium hardness and bromine or chlorine levels.Applications:Normal:Dip strip in water one time.Compare test results to chart on back of bottle.Tips:Low calcium hardness levels can cause foam and corrosive water conditions, so use a strip that includes the calcium hardness test.Compatible With:Chlorine, bromine and ozone sanitizers.Advantage:Part of the Simple Spa Care Program. Patented PopTop protects strips from moisture and UV light.