I put 10 in a RSM250, 66 gallon that was infested. Took 4 months and now I can't find any Aptasia in my tank. Some lament that berghia will die after Aptasia is gone. Aptasia is their only food source, however, they will get the job done, just have to be patient. They are nocturnal so keep you eyes peeled 1-2hours after dark if you want to see them. They will eat Aptasia from inside out, so you won't see any berghia for a while after releasing them. Do not release them into the Aptasia, because the Aptasia will eat them. Best $275 I have ever spent on my tank. Only if the Apex was as reliable. I have tried everything, but berghias are the best option for absolutely getting rid of Aptasia.