Salt is available from all leading pool shops and most hardware stores (try and get your hands on the cleanest available).
 

Formula to calculate required salt for the watermaid chlorinator is Length x Breadth x Average depth x 6/50=50kg bags needed for pool as initial startup.
 

Salt is not lost through the process of chlorine manufacture, only through splash-out, backwashing, draining or excess rain.
 

The average pool loses one third of its volume each year.