So cool, peachy! I've always wanted to know more about this sort of thing. I use marine-tank vacuum pumps to make climate-control systems for museum cases at work, and so I've gotten into watching YouTubers who are aquarium-keepers. Much respect.
My high school biology teacher explained it to our class once, people who buy coral trinkets while on vacation contribute to mass coral harvesting which happens even when the colony is alive. Both pollution and this mass harvesting contribute.
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