i just got xenia and it isnt looking good. so i was told to post my paraments. i have a 20g with 65w pc.
alkalinity-14
ammonia-0
calcium-400
nitrate-5
nitrite-0
PH-8.1
phosphates- they just put a " -- "
salinity 1.023
This might be more curiosity than an answer but do you use tap water or ro/di? from all my years at my lfs it seems that some people just dont do xenia well despite keeping more "difficult" corals. it seems like mroe of these people use rodi. This leads me to think that xenia like slightly "dirtier" water with more nutrients. i dont know a real answer tho
I wouldnt put the flow directly on them but put them close so they sway back in forth gently in the current. Your lighting should be okay so if that doesnt work you may have to try putting them in a few different spots before they find a place they really like.