I've had it for a month. When I got it, the teeth were already exposed, but weren't brown yet. I hope it comes back too. I'm just going to leave alone where it's at on bottom now and hope for the best. Some bits of the red coloring have gotten darker since I've had it, so I'm hopeful that's a good sign. Should I keep blasting the bubbles away once in a while? Since everything else seems to be going well with the tank, I really think it will get much better once I can change out all the bulbs next month. I think these "aging" bulbs that came with the fixture have probably caused more problems than anything. Just my theory though.