i would suggest talking ot your LFS and taking it back.
reasons why i say that..
1. Flower pots as a whole do not do or rather live every long in a reef tank. I had mine maybe 7 months before it slowly died.. i thought it was doing great but not really.. even though they look great inthe "shop" and seem health there usally are slowing dieing.
2. they like only certain spots in the tank. not too much flow on then and not too little.
to answer the feeding, spot feeding then usally works wonders. if you can make a cone to sorta cover it when it is open that will keep most of the food around them.
sorry this many seem like bad news..really trying to help
