Scaling and fouling of membranes are an on-going performance issue for most plants This presentation outlines innovations in speciality chemicals designed to inhibit membrane scaling and fouling and to clean membranes where deposition has occurred. There is an increasing trend to treat recycled waste water and use it as a feed supply to RO plants. Resulting high levels of phosphate can cause rapid scale formation in the membranes. This paper discusses phosphate chemistry and field trails of a new antiscalant which overcomes the need for acid dosing. Specialised nanofiltration membranes, have been developed for the removal of sulphate from seawater in offshore wells, reducing scale formation and souring in the well-head. The membranes are subject to barium/strontium sulphate scaling. This section discusses the processes and products developed to inhibit scale formation. Clay is a common-place foulant and very difficult to remove from membranes. The paper also describes the mechanisms and products developed to remove clay effectively. A number of case studies are described.