white Coralline Algae

[biff2100]

My Coralline Algae seems to be turning white mainly at the top of my tank, do you think this is due to the temp control or something other than this. I have been checking my SG and today I've just noticed that it was 1028/9 a newbie mistake, I hadn’t calibrated my refractometer since the day I got it.

SG now on its way back down, I'm also taking this as a reason I have been able to keep polps for a few months.

 

[MacDracor]

Each species of coralline algae has a very specific set of requirements with very little wiggle room. The factor we encounter most often is lighting. It's not uncommon for someone to replace old bulbs and be shocked that half of their coralline dies within days, only to be replaced by a different color. What has happened there is that the kind that died liked lower light, and when the bulbs were replaced, the intensity increased beyond their tolerance.
In your case, I would guess it is the SG or temperature. But it may bounce back once things are stable. I've had patches start to turn white, then suddenly recover.