About a month ago I started getting serious about akc/calk levels, adjusting daily etc, within a week a dark spot appeared on this donut, I poked it with a stick because I thought a piece of rubble had fallen onto it, it was attached to the coral. at times it disappears under the fleshy part which is a much lighter color than the rest.Well tonight it popped out again and its 4 times bigger. Any guesses??
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