I don't know if your still working on this breeding effort, but when I helped breed the Orchid we had better hatch rates when we collected the eggs and the male the evening before hatching and transferred them both to the hatching vessel. We managed this through the use of pvc pipes like your using and just covering the entrance while the male was inside with the eggs. This allowed the male to care for the eggs up to and through the hatching process which usually occurred around 8-9pm. Also during my study of the Orchid I found the strongest feeding response on rotifers at concentrations around 20/ml hope this helps. Also depending on your copepod population i found increasing feed effort as copepod concentration increased though i only investigated up to 1/ml. If you like to read ive attached my paper