May 22, 2017 #1 shrimpandram Aquarium Advice Activist Joined Mar 15, 2016 Messages 141 Is my lr getting purple algae? I am excited for this
May 22, 2017 #2 Sniperhank Giant Clam Addict Joined Nov 18, 2011 Messages 20,651 Location Summerville, Pennsylvania If it is hard, then it is coraline. If it blows off, it is cyanobacteria.