Hi, (if the problem is low water levels) a pump exposed to air will sent air bubbles out everywhere. So the pump of your skimmer has to be under water.
NEVER add salt to your tank. Always premix any saltwater in a separate tub, and let it churn 24 hours before use, or at least 12.
Do you top off your tank? Everyday a little water evaporates, but the salt doesn't. Just add enough fresh RO water to bring the tank water back to the original level.
Unless you had some major leak, refilling to the regular water line with freshwater is not going to dilute your saltwater to any dangerous levels. The only way too much saltwater is removed is if you were removing and emptying the skimmer cup many times throughout the day...(wet skimming). Otherwise there is no need to replace any saltwater at all.