The first thing to buy is James Fatherree's book on clams (if you haven't done so already?). Light is the number one focus with clams, so no matter what species, be prepared to have enough light (and right spectrum) to keep the clam happy. I'm not going to start throwing out numbers, but always have enough light in reserve to meet the clams needs. My other piece of advice, don't buy wild caught clams, especially maximas, they simply don't last without massive amounts of light, even then they tend to not live long term. I would wait until you have the tank dialed in and corals are thriving before adding a clam, it will make your life (and clams) easier. Derasa and squamosa are more forgiving, but they get big, so you'll need space for them to grow. Maxima and crocea are the hardest to keep, as they both require a ton of quality light. I personally hate clam cradles and tend to use live rock as an anchor/attachment point. Look for natural places in your rock work that a clam (maxima and crocea) can "sit in", as this will provide them the best area to attach. As others have stated, daylight spectrum is the best way to view/grow clams, nothing else compares and blue light absolutely sucks for displaying the awesome colors of their mantles. I think you can crank the lime channel on the Reefi's to get a whiter look/spectrum, but you may want to consider a "spot" light to highlight the clam?