Coralline turning white can also be a sign of low alk & calcium. If you want more coralline than you can shake a stick at start dosing Kent Tech CB (Part A&B) or another balanced calcium buffer every day. In a month or two you will be scraping your glass with a razor blade you'll have so much (just make sure you measure it so you don't overdose)! If you want to get really serious get a calcium reactor!