I know that you have heard from people that mollies need salt. They do indeed tolerate a great deal of salt but I have great success with mine with no salt added at all. The amount of salt really does not matter for the fish themselves. Mollies can live in almost any water that has a high pH and is fairly high in mineral content. My fresh water has a pH of 7.8 and contains a TDS of over 200 ppm so I use it straight from the tap for my mollies. If you have soft water, adding some sea salt will bring up the pH and the mineral content, which may be why people think mollies need salt. If you are adding salt, use the same stuff they sell at the fish shop for setting up a reef tank. An old trick to cycle a saltwater tank, without risking any high dollar fish, is to cycle it using mollies at full salt water tank strength. Mollies are very adaptable.