If you can, buy some fully cured live rock that already has purple on it. This will help get it in there and start to spread out. I used dry rock that I ordered so my tank was white for a long time. After my cycle I started adding coral which came on live rock covered in purple coralline this is when it really started to show up in the tank.
Also I tried purple up, it what the lfs
owner suggested lol, did nothing for my tank. In fact I was having issues with my test results being all over the place. I put a stop to adding chemicals and like two weeks later a lot of my problems started to go away.