Unfortunately, most of the time barnacles don’t last very long in reef tanks, as they’re non-photosynthetic filter feeders with heavy microfauna (phytoplankton/zooplankton -i.e. pods, rots, BBS, etc.) food needs (like NPS Sponges) and many barnacle species are from temperate waters (so they don’t do well in our tropical reef tank temperatures long term).
If the species can handle tropical temperatures year round and your tank has plenty of small foods readily available in good quantities, then the barnacles should do fine. Otherwise, they will eventually die. As they are similar to NPS sponges, if you have some NPS sponges in your tank, you might be able to use them as a crude gauge of your tank’s ability to handle the barnacles, but there’s no guarantee of success with this method.
