hi there harold,
not to disagree per with bcollins, but just to share my thoughts with you. i don't think the puffing up behaviour of your goniopora sp necessarily suggests ill health. it could very well be a physical response to available particulate matter that may be uptake by water absorbtion as opposed to direct tentacle capture. likewise, it could be a mode of excreting wastes, or simply a tentacle retration response from inverts or fish having agitated it by swimming past, etc
in my honest opinion, the swollen tissue of the goniopora hints at good health as opposed to bad health. they totally retreat into their skeletons in those situations. normally, when your gonio is fully extended, it seems as if just its elongated tentacles are extended, but if you notice carefully, its actual base tissue is also swollen, creating a swollen hemispherical shape from which the tentacles then extend out.
perhaps try feeding the colony more with particulate foods of appropriate size, like Reef Roids or DT's oyster eggs, and see if it responds? if it doesnt, perhaps relocate it to another location where flow is slightly higher?
hope that helps in one way or another. do let us know how your gonio comes along ya.
cheers,
ian
ps: thought maybe id share some pics of my former system with you- a gonio sp tank before i graduated and started work:
tank pic:
a gonio columna sp i think, in full bloom so to say:
and once in a while when it feels like acting goofy it does this- not sure why it did:
these gonios were with me for about 2 years prior to my decommissioning that tank. no reef roids then, so i fed mashed mussel roe, crushed cyclopeeze and nannochloropsis sp. phyto daily. also cleaned my tank furiously each day and changed 10% water twice a week due to the high bioload