I swear, this hobby annoys the hell out of me sometimes. You can try to do everything right and still...
I started this new tank with all brand new rock trying to avoid vermetid snails. Scrubbed all the branches on the torches before I put them in with h2o2 to try to prevent it, removed frags off plugs, etc. Still end up with it.
Same goes with asterina stars, not even sure how this even got in my system, but now I just manually remove 1-2 a day as I see them.
The latest and greatest that really pisses me off is aiptasia! I haven't added any LPS in months and when I did, as I said, I scrubbed the hell out of the skeleton. SPS all were removed off the frag plug, some that I couldn't, I cut the base off and grinded down the plug to the flesh along with h2o2 dip just below the flesh. I find one this weekend!! I made about 2 fl oz of kalkwasser, smothered the entire thing with it, then vacuumed out about 15g of water in the area. Ugh... This hobby.