Relations between algal populations and the pH of their media

Natural, mixed algal populations grew well in artificial culture media of different pH levels between 5 and 12. Algal growth caused marked changes in the pH of the culture media, raising the low pH values and lowering the high ones. Within 3-4 weeks all cultures reached the pH range of 8.5-11.0, while sterile controls retained a much wider range of 4.0-10.0. Final pH values were temperature dependent, as also was the rate of the pH change.