Well, it's been around a month or so since I took down my kessil lights, took out every coral and placed 2 emerald crabs into my 75 gal. I gotta say, those are doing a good job eating up the bubble algae. Since there are no lights over the tank to aid in the growth of BA and my fish eat all the food I give them. The emerald crabs really only have one option for food, the BA. I do plan on getting 3 more emerald crabs to help them out. Hopefully I will be able to add the corals back in and put the lights back up by Christmas. However, the tank that my corals are currently in, has some HA. I hope this won't transfer to my 75, seeing how the 75 has a simmer and fuge. But, I've seen emerald crabs eat HA too. Anyways, in my case, yes emerald crabs eat BA.