I use saltwater lines in freshwater all the time. Freshwater lines in saltwater too. A saltwater floater will not float as well in fresh water since it is designed to float in saltwater, which is less dense. However for most situations this will not matter. I have used some of my tropical lines for bass fishing in Southern California during the heat of late summer and early fall when water temps approach 80 deg F and Air Temps are 80 to 100 deg F. If conditions are too cool a tropical line will be stiff and coil. Non tropical saltwater lines will be just fine.