If all your parameters are good, you have good lighting (I kept them under 250, 10K or 6500K for years), you're feeding, etc. then it sounds like its getting more zooanthalae. Sometimes the bringt pink/light coloration is actually bleaching. At least that's my experience. There are some lighter colored roses but most of the time it's because they are bleached out. What's your lighting and water params?