Tried both but as Bri says they do last a bit longer outside providing you keep a eye on them,keep a eye on the weather forecast in case the temp drops right down.Seems like most tackle shops are using peat now,they look fresher in peat but its messy.Bri kept mine in sea water before just keep changing the water never used a filter mind and they lasted about a week but may keep longer as they were fine when i took them out