Hi Debi,
It's a good thing that your plate is aquacultured. Aquacultured corals indeed have a much better survival rate than wild caught specimens. Aquacultured corals, as you already most likely know, are already adapted to life in the aquarium. You may see much more growth from your specimen than you would see in a wild caught specimen. While they may be adapted to aquarium life, this doesn't make them easy-to-keep. I have had nothing but bad experiences with the plate.
FWIW,
Plate corals enjoy medium currents with ample amounts of lighting. The plate will do best in the substrate (preferably a small particle substrate to prevent any damage to the underside). You're best off feeding foods such as Squid, Shrimp and Krill 3x weekly. You may see some deflating (sometimes inflammation before/after the deflating) in the coral if you feed foods which contain bones, scales, or any other matter which cannot be digested (foods such as Lancefish, Silver Sides, etc.).
dt's
I highly doubt that your DT's phytoplankton is being consumed by your plate. Plates are not herbivorous, thus, will not pay attention to phytoplankton or any other herbivorous foods. Most likely the phytoplankton you're adding is stimulating other forms of life, which the plate is feeding on.
Good luck with the plate!
Take Care,
Graham
PS. I attached a picture of my plate.
