Here's basically how it works, at least what I've went through in raising/breeding them:
Under 1" : PC lighting, the mantle is EXTREMELY fragile
1-2": Can handle a more intense light such as a T5, but again, mantle is still very fragile
2-3": can handle longer periods of intense lighting from a T5, or low levels from halide. Handle is still fragile
3-4": good time to introduce higher intensity lighting such as MH or LED. Caution needed with a good LED fixture, especially if it contains optics which can burn a mantle, especially if the clam is still on the smaller side
4+": bake those bad boys!
With larger clams in the home aquarium, you have better luck with "placing them anywhere" so to speak. They can better manage different lighting than a smaller clam can. That being said, a Maxima (which requires more light than a Derasa) will thrive under more intense lighting and will grow quicker.
I have a 7" Maxima right now that has grown much quicker under my LED's with optics and being placed at the top of the tank than it did under my metal halides a year ago.