Hi Brett. When I first got into the hobby, my first coral was one I got at PetCo...and yes, it was a "flower pot", or more specifically a Goniopora sp., most likely a Goniopora stokesi. Gonioporas, along with the similar family, Alveoporas, are found in sandbed flats in lagoons, and areas of calmer and turbid water. These waters are much more rich in nutrients, than the waters around fringing reefs, or those where waves create water motion suitable for acroporas, and other hard corals. Along these same lines, they receive much less lighting that clearer water areas of reefs.
Gonioporas do not have a very good life record in reef aquaria tanks. The one I have kept from PetCo lasted about a year, and even reproduced asexually by satellite budding or ejection (i.e the creation of miniature specimens of the same species). However, after that, things went downhil and I started to see tissue rot, and eventually the entire coral rotted, and I tossed out the skeletal base. There are a couple species that can be readily attainable for hobbiests. The better one to choose, if you are indeed...wanting to plunge into keeping one of these suckers, is to find the Red Goniopora, and...the even rarer Purple Goniopora. These have better track records in our tanks than do the regular metallic green/brown gonioporas that you probably saw.
One reason they sell them cheap is because just what I said above--mainly that they will not thrive long in the tanks of LFS, and what better way than to sell it cheaper? I would advise, from my experience with this coral, to spend the money on other frags that would have a better chance. I'm not telling you to NOT buy the coral, but to research it a bit further.
Gonioporas will not affect nitrates very much, at least not as much as clams, as they need small amounts of nitrates to thrive. Key for this specimen is definitely lower light than MH, or if running with MH, keep them on the sandbed (as it is naturally found in nature), and indirect current that will sway their long tentacles in different ways.
I hope that helped a bit. I can post a picture of the baby "satellite" specimens that the mother colony ejected if you'd like.
- Elmo
