How do these systems work? They need to be assembled "ala cart", depending on what specific functions you want the system to perform. The Goldline Controlls Pro logic is a main control system only and is selected based on the number of relays, which relates to how many functions you want it to perform. It is used to control the pool equipment and accessories. If this control is used with the optional sense and dispense, the control system will turn on what ever type of chlorine system you have. If you have a solid feeder it will power a solonoid valve to open up and send water through the chlorinator to put chlorine in the pool. If you have a liquid system it will turn on an Chlorine pump to inject the liquid into your return line.If it is used with the optional salt cell, it will energize the cell when it calls for chlorine and turn it off once it reaches the level you have set it to In addition, it will test the water for proper ph and turn on what ever ph adjustment system is needed. Additional relays are used for lighting, fountains or any other ancillary equipment.