Water Testing Strips like the AquaChek Test Strips can be used to test for individual chemicals or you can buy something like AquaChek Select 7 Way Test Strips or Yellow 4 Way Chlorine to make multiple tests at the same time.
Most second-language speakers reside in Francophone Africa, in particular Gabon, Algeria, Mauritius, Senegal and Ivory Coast. In 2015, French was estimated to have 77 to 110 million native speakers, and 190 million secondary speakers. Approximately 274 million people are able to speak the language. According to a demographic projection led by the UniversitÃ© Laval and the RÃ©seau DÃ©mographie de l'Agence universitaire de la francophonie, total French speakers will number approximately 500 million people in 2025 and 650 million people by 2050.
The statistic shows the most spoken languages worldwide. 1,500 million people worldwide speak English, of whom only 375 million are native speakers.