Have you made any changes to the tank? Lighting (new bulbs), flow, just a simple change here or there will do it. Dont worry. In time it will return. Maybe in a new color but it will come back. Keep an eye on everything else in the tank just as a precaution.
I got a new T-5 fixture a month ago. I thought it would help grow more corraline, not less! The new light is nearly double the wattage of the PCs I had on before. Thanks for the help, I hope it comes back.
Cahnages in light will do that. Not a big deal. Just give it time and it will return. Probably in a new color but it will return.
Coraline is a funny thing, it can take for ever then it can take over! Dont worry to much! Just keep the tank stable and be p[atient. Youll be scraping it off of the glass soon!