Per the manufacturer, the SolaMist Misting System tubing is about a quarter of an inch or 6mm in diameter.
SolaMist Pro Concentrate is made to be used with the SolaMist Mosquito and Insect Misting System and the SolaMist Misting System Tubing and Nozzle Extension.
According to the Owner Manual for the SolaMist Misting System Tubing and Nozzle Extension, they recommend that you space the nozzles 3 feet apart. Please see page 5 of the Owners Manual for detailed instructions for installing nozzles.