Jim,
Funny you should put it that way, I sometimes have trouble not laughing when I hear some of the advice given at the LFS. My rule is this, listen to everything, anylize the info, and get mutiple opinions, Skepticism is not a crime as long as you aren't rude. But just because someone works at a LFS doesn't mean they know of what they speak. Also remember that opinions of a successfull experienced hobbyist are far more valuable than those of a trained employee. Good luck, and keep the gravel clean, the buildup will be immense if you wait six months.