Name of TV series with an alien thing and some triangle weapon?
When I was a kid I watched this TV series about a teenage girl and I think her father was an alien (whom you never saw - maybe he was dead?) and she could communicate with him I think via a thing on her bedside table. And in the end, there's this alien - she and her friends think it doesn't like water so they lure it to this place with lots of water, but it turns out that they were completely wrong and it travels via water. I think it gets killed at the end by the girl putting some kind of triangular device (energy weapon?) inside the alien's body.
Can anyone help me remember the series title?
PS. Perhaps I'm mixing two TV series together in memory...