It is the fact that white grub is encysted that makes them tough to kill. Salt might very well kill a white grub if it is loose in the water given enough time. But you simply cannot soak a freshwater fish long enough in a strong enough solution of saltwater to kill an encysted parasite. It does work very well for ectoparasites like I mentioned above, and also for ich. It wont do much for the actual ICH on the fish, but Ich has a short life cycle, and during its freeswimming form, it is highly susceptible to salinity. So with the right amount of salt, it cannot complete its life cycle, and dies out
If I might add, Ich can also be controlled by manipulating water temperature in a tank. Fortunately I've never experienced Ich and hope I never will.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.
