IMHO, the only way to really control the population is with peppermint shrimp. I have one in my 29 that was quite literally loaded with aptasia. Tried everything, aptasia-x and similar, kalk-paste, lemon juice...sure they would kill the aptasia, but they always came back. Bought a peppermint shrimp from Phishys and were all gone within maybe 10 days.
I have even re-introduced a few into the tank via frags and saw those dissapear within hours. Peppermint shrimp, end of story.