mine definitely seem brighter after a feeding (roti or mysis mixed with plankton), I also started my rainbow on sand, moved up and it is now on one of the lower rocks and seems to love it there, 2 new polyps forming already, orange middle, blue ring, red/blue outer part.
Waiting to see what happens with the purple/green one I added a cpl days ago.
(36" 4bulb T5, 2x blueplus, 1x purpleplus, 1x actinic)
I am also switching to LEDs in the next month or so and will start with low settings to acclimate.