Just dont bother with them. They are supposed to be cold water clams and prefer very deep sandbeds. They dont do very well in captivity and although the ones that live do reduce nitrates, the ones that die, do so in your sandbed and most people never find them. (huge spike in a 12g) Just go the regular route and reduce your trates with water changes supplemented by a fuge. Chaeto and caulurpa reduce nitrates and dont require any care.