[pogodzib]

What kind of polyp is it? Most polyps are easy to keep so that would be the coral that I'd focus on. Xenia can be tricky if that water parameters aren't what they like and will melt away. Since you say that you've been working with your LFS for 6 weeks and you're experience says 1 month, I'm going to guess that your tank is 6 weeks old. Even if the tank's water parameters are all testing good, many times people corals have a tough time surviving in a tank that young. At this point, it won't hurt t o do a water change and move the location of the polyp higher in the tank if possible to make sure that it is getting enough light. Spot feeding the polyp may also help, but in a new tank, that can be very dangerous since it could cause a major second cycle. Also, if your tank is that young, you shouldn't have that many fish in your tank yet - which again leads to how stable your water parameters are. Please, let us know how long the tank has been set up? It is very important for everyone here to help you figure out why yo are having problems.