I did it. Took about 2 weeks for my clam to get used to everything fully. First couple of days it was open, then stayed mostly closed for a week, then open and closed, now seems to have gotten used to it all.
LFS has some little ones (about 2" long) for $15. I don't know what kind they are though. I think they are crocea. I'm told they will max out about 3" or maybe 4" in my tank.
I've been wanting to get more light. I was thinking of a clamp-on MH light. Even 70w or 100w would be a huge boost to my lighting with such a small tank. Just 70w would put me up to about 7 watts per gallon. Combination of T5 and MH lights.
With a lighting boost like that, I have no doubt a clam would thrive quite well.
All it takes, is money. :twocents::twocents::twocents::twocents:
Seriously,I believe you will be fine with what you have.If they are not attached to a rock,place them on small rock on the sandbed,let them attach to the rock then move them up halfway up.