I am no means an expert but I have had luck keeping a few in my mixed aquarium.
The orange, blue and green Ricordea are located in medium flow and about 2/3 from the surface under t5 lighting. They receive direct lighting (not shaded). Water parameters are stable (cal: 430ppm, alk: ~8dkh, mag 1350 ppm, salinity 1.026, nitrates, trites, ammonia: all are undetectable) There is space between them and other corals and also positioned in an area where crabs and other inverts don't pester them. I have found they benefit from 2 x weekly feedings of dried coral food and targeted feedings of high quality frozen food such as mysis, rod's food, or similar.
Good luck!