Yes it's sea water I tasted it before when it filled up and when it filled up again. No worries on being harsh it's pretty ugly in there. It isn't a hole though it looks like the hoses for the AC run back through there and it is covered in some sort of plastic. I'm wondering if one of the hoses is carrying raw water back to cool the system and it is leaking somehow. This would be odd, however, since the system was not running while I was gone this past week. I've emptied again - 5 day countdown begins - how does one work when this is waiting for your return.