coraline algae

ron garnett

New member
It looks like my coraline algae has "crystallized". It was spreading and growing quite well and now the coraline algae has turned a light purple with tiny white specks in it. And it seems that it's ceased to spread. Could it be that my alkalinity is off?
It would be nice to know what your water parameters are, particularly magnesium & calcium which are needed for coralline algae to grow properly. Light could be a factor also.

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New member
I've seen corraline do that sometimes.

Have you changed your bulbs to a whiter color recently? I've seen some of the more purple corraline grow well under deeper blue colors, and if you change to brighter white, the purple may "atrophy" and be dominated by the lighter pink colors.


Premium Member
I doubt alkalinity will have much to do with it but decreased calcium and magnesium may. Lighting also.

I would do some testing and check your numbers. Something has obviously changed in your tank.