For clarity, check with the supplier the arrangement of the 0.3μ bacterial membrane. It is installed after the RO membrane, instead of before. Microbial membranes are typically installed before the RO as an additional support to minimize acceleration of the fouling of the RO membrane. Fouling of the membrane causes irreparable damaged . Relative to this, Pseudomonas aeruginosa a common water borne microorganisms and forms biofilm can pass through the 0.3μ bacterial membrane and requires at least 0.2μ to filter.