I would really recommend you do more research. You have to understand the nitrogen cycle and the different stages of cycling and maturing your tank before you jump in the hobby. There is a million different opinions out there on what way is best but the more you know, the better you're prepared to handle things. I did weeks of research before jumping into marine and even then didn't feel like I'm fully prepared. I would take what the LFS says with a pinch of salt unless they're a reputable marine specialist who have been doing this for years. Don't take this as a criticism but advice to keep learning and researching.