... The species Thalassiosira weissflogii and T. pseudonana are available from Reed Mariculture. They're the perfect size for many species and I've seen a lot of success after adding them.
Just did a little more reading on corals consuming algal nanoplankton and was facinated to find that even Tubastraea coccinea is able to feed on T. weissflogii and T. pseudonana. Never would have guessed that given the large polyp size. I'll go ahead and get some from Reed and start adding it to the food blend I'm mixing for my NPS tank. Thanks for the heads up.