Nelsen Arsenic Reduction Systems  feature the 7000PID (Nelsen proprietary controller) arsenic reduction control valve and LayneRT adsorption media. The 7000PID is a non-backwashing controller programmed for the specific water chemistry for each installation. It indicates system capacity and the remaining safe levels of media adsorption. LayneRT is a proprietary, durable, arsenic-selective media. It is a reliable, high-capacity technology that effectively reduces arsenic to safe levels.