Hi, I'm an admitted new salt water hobbyist and have set up a new 12 gal
reef tank. For the last week, everything has been pretty benign, with no noticeable differences from the first day. But this evening I walk in my office and see brown spots on the back wall and on the sand. I know something is going on, but what? What's next? What should I expect! I'm super excited about the experience and my son was super excited when I pointed out the spots. Of course he asked, "Why?," and I wasn't able to easily answer.
Any simple answers that might help would be greatly appreciated!