This is one of those delightful recurring threads!
I tried Aptaisia X/Kalk Paste and just made the problem worse for me.
Then tried Berghia Nudibranch and they did a great job but didn't get them all before my coris wrasse killed the adults and the random pods in the tank will eat the eggs I found out, so adults only for me in a mature tank with no coris wrasses!
Then I tried Peppermint shrimp for the second time. The first time I got one and it did nothing. He was killed by an arrow crab so I got rid of the arrow crab next. Then I bought 6 peppermint shrimp because they were on sale and they totally wiped out the aptaisia in about 2 weeks. Big ones in hard-to-reach places too. BUT, and it's a BIG BUT, I had heard they will hurt/prey upon LPS corals. I only had one Trachy in the tank so I pulled it up and put it on the frag rack to see how the shrimp did and if they tried to get up there. They never climbed up to the frag rack, so I put it back down on the sand bed. about 3 days later I woke up to a severely damaged trachy that had its insides pulled out while a peppermint shrimp was having a nice meal.
I have also tried Aptaisia eating File Fish, but they always seem to go for the LPS and Zoas as well.
I am 0 for 2 on file fish and they have cost me at least $100 in Acans and the Zoas survived once I pulled them out.
I am 1 for 2 on peppermint shrimp for eating aptaisia but 0 for 2 in getting some that won't eat expensive coral. I will probably have to buy a dwarf fuzzy lion or something to get rid of them. I suppose I could try and trap them first!
I am 1 for 1 on having Berghia Nudibranch, but the Coris Wrasse and pods in the tank caused their eventual demise.
The only 2 that didn't work on aptaisia for me were the file fish and the Aptaisia X. The Aptaisia X/Kalk paste will kill them, but it may also cause them to propagate worse, and it is impossible to reach some of the ones buried in the crevices of the rock.
So the 2 that did work were the Berghia and the Peppermint Shrimp.
The Peppermint shrimp is a great way to go but you will need to pull or relocate the nice LPS corals like Acans and Trachy's so they don't go after those for a convenient meal. Also someone above mentioned having one and it did nothing but when he added a second one they went to town and wiped them out. I think there is truth to that because that was essentially my experience as well.
If you don't have a coris wrasse or if you want to relocate yours while the berghia are doing their thing, that is probably the best way to completely clean the tank of Aptaisia. If you have pods, get the adults. if you don't have pods, they will reproduce and you can sell some to fellow reefers! I think Bristle worms might also cause problems with Berghia reproduction. They will probably eat the eggs like the pods do.
So, If anyone wants the 6 peppermint shrimp I have to clean your tank, I may be listing them for sale in the near future! If I get another scoly or trachy I will certainly pull them out and put them in the smaller nano tank...