DT's is a live phytoplankton culture of the green algae (technically a member of the Eustigmatophyceae)
Nannochloropsis oculata. Although it is possible to grow the stuff at home (check out
this article detailing how it is done), it is not generally worth the time and effort that it takes, and most people who have easy access to
DT's phytoplankton prefer to buy it (myself included, and I have plenty of experience growing phytoplankton)...
There is a collection of my various posts on phytoplankton archived
here, and a while back I gave a talk on phytoplankton foods for the reef aquarium that is now posted online
here. There are also some nice microscope images for you to compare some of the most common products posted
here. Finally, if you're interested in more detail or information, I discuss the various types of plankton foods for reef tanks, what they are, and how well each brand worked in detail in my article in
Marine Fish and Reef USA Annual 2002.
Hope that helps.
Rob
[ 30 April 2002, 19:31: Message edited by: Biogeek ]