Coraline disappearing?

My tank is about to hit the 3 month mark, and i noticed that all my coraline is turning white/dying. After about 2 months it started growing like crazy and now i have nothing. What would cause it to stop? Nothing has changed.

 

I would say a drop in alk. It usually does best under high alkalinity conditions (i.e. 9+ dKH)

 

Any change to your lighting? Increasing the lighting can cause a lot of it to die off before a higher light species takes its place.

What about water changes? Is it possible that the water level was dropped for too long during a water change?

Other than that I'd say look at alkalinity, Ca and Mg like the others have suggested.

 

its been about a week since i have tested and everything was almost perfect, but ya i did just bump up my lighting quite a bit...went from 260w PC's to 8x54w T5HO

 

Sounds like the lights then. I made the exact same upgrade in December and my coraline also declined. Coraline seems to like the actinic spectrum. Try adding more actinic bulbs to your mix. If your fixture has multiple cords and use timers to turn on the actinics first for a few hours before turning on the rest of your bulbs. At night leave the actinics on for a few hours after turning off the other bulbs. The coraline will eventually come back.