If keep your CA
above 400 and do regular water changes, you won't need to add MAG or Purple Up or anything else for coraline to grow. You could seed your tank with some purple coraline scrape-ings from a friend or the LFS
. This will help it grow if you don't have any right now.
Coraline also comes in different colors depending on your lighting and water params.
Here is mine with 91watts PC
and 440 CA
29gal BB | 42+ lbs LR
| 143watts PC
| Asst. Leathers, Frogspawn, Hammer, XLG Open Brain, Zoanthids, Mushrooms, Diploastrea heliopora | Blue Mandarin | Atrosalarias Fuscus | Pair Captive Bred Ocellaris Clowns | Peppermint Shrimp | 6 Astrea's |