I just started a 55 gal tank. I am new so I have bee following LFS advice and did not find this site until after I started, first mistake. I have a 55gal tank with water 40 lbs of live rock and 20 pounds of crushed coral. Using a Refugeum as a filter. I have read here to use sand and lots of for your substrate. The LFS recommended the crushed coral. I would like to end up with a reef tank and not a fish only tank. Can I add sand, remove crushed coral, or what. I am now at a stand still till I figure this out. don't want to waste anymore money of stuff like crushed coral if not needed. Thanks