Abstract: A fluid monitoring and control apparatus and method including providing a programmable and reprogrammable control unit comprising a display, user inputs, and input/output connections; placing a programmable logic controller in direct communication with the control unit, which programmable logic controller is programmable and reprogrammable through the control unit; and placing a plurality of fluid parameter sensors in direct communication with the control unit. The invention is also of a fluid control apparatus and method comprising providing a membrane and estimating salt rejection by the membrane.

Abstract: A fluid treatment apparatus (100) and method having a variety of interchangeable input/output cards (10) capable of communicating with a variety of parameters including analytical parameters. A programmable central processing unit (124), input/output cards (10), data bus (30), display (102), and keypad (104) are integrated into a single integrated apparatus (100). Analytical parameters are received directly by the appropriate input/output cards for direct communication with the central processing unit (124). The central processing unit also outputs control parameters through the input/output cards.