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Snails might, and could be acclimated to a fw environment, depending on the type. Are you planning on getting a salt water tank to feed your seaweed to?
They have a SW tank, just want to get rid of some of the macro from a fw setup. I'll be honest, just pitch what you are trying to get rid of. It isn't worth the effort, even if the algae wouldn't just rot away when put into sw.