I am planning lab experiments in open columns with DI water and various inorganic particles, lasting per months. The columns with suspensions will be exposed to the sunlight or to artificial UV radiation (300-400nm). I would like to avoid any contamination by microbial in the columns. What would you recommend me? I consider thymol, but I do not have any experience with such kind of chemicals, and I would like to avoid also using of any additional substances in my system. Could strong UV radiation be enough to avoid the microbial effect?

Thanks in advance!