I agree with everyone else!
For feeding, you should remove the clam to a small, seperate contained where you can dose DT's, rather then overdosing the entire tank. Do not try to feed them with a turkey baster or some other similer tool. Clams do not respond well to sudden feeding like that.
HTH
RE
ps definitally on the sandbed, but you may want to move him gradually upward if you dont have much lighting