Clam taking nose dives

[Delphinus]

My take is that if it doesn't like the spot then there will probably be other things you can notice, like, not opening or extending as much as you think it ought to, and so on. In which case you can try a different spot then. But basically as long as there is good light getting at it and current isn't too insanely strong, and nobody is picking on it, then it's probably going to be OK anyhow.