I agree with what others have already said. LPS tend to throw longer sweepers in heavier flow. I am surprised that a Welso would throw such long tentacles.
Support the non-profit Reef Stewardship Foundation with the iSearchiGive.com search engine, donate a penny with EVERY search. Find out more information by following this link to the RSF iSearchiGive.com search program.
Just an update I actually seen this tentacle extend out during the day once now and it was rubbing on some mushrooms about 4 inches away the mushrooms have not seem to shown and response negative or otherwise.It is really cool looking i wish i had a camera that could catch this on film lol my camera just doesn't pick it up.