Maveri- on that last comment when I bought my Maxima there they also told my to buy DT's. Im not trying to jump on the band wagon just letting you know.
Andy- here's my understanding. The success rate does not lean towrads feeding, as you have put it. Clams can generate more than enough energy from photosynthesis alone to live and grow normally. The supplemental feeding may not have hurt, but it hasn't shown to be a benefit either.