White mouth eel + turbo snails

I have a beautiful whitemouth eel named Jetsam. I know he don't play nice with anything, but I thought maybe a turbo snail would be ok. I've already tried adding 3 turbo snails over the course of the past 5 months (not at the same time), but they keep dying.

I don't think Jetsam is killing them (although he sometimes tried to bite them), but none of the snails have lasted more than a month.

All the stats are normal. Nitrates are usually around 30/40ppm, but nothing I try keeps them down. I just have to do weekly water changes. I'm thinking it might have something to do with it being a newer set-up. And the fact that Jetsam obliterates his prey making a huge mess each time.

Jetsam seems to be fine though. He eats everything I give him (live and frozen food about three times a week) - he's always ravenous and active.

Any suggestions or ideas on why the snails keep dying?

Also, any suggestions on anything I can put in there that he won't try to kill and eat?