A bit confused .. bought a 50gal tank with live rock and live sand. Set up with a protein skimmer and was told by seller to just let cycle for few weeks before adding any invertebrates. I have not added any food or ammonia to start a cycle - do I need to? He didn’t explain that very much and don’t want to mess up when I add my fish later and it’s not ready. Seeing a lot of info online and hard to understand it all. Thank you!