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.
Instituto Cervantes claims that there are an estimated 470 million Spanish speakers with native competence and 560 million Spanish speakers as a first or second language, including speakers with limited competence and more than 21 million students of Spanish as a foreign language.