Im about 9 days into my Nitrogen cycle, the ammonia and nitrites have leveled off and I have a nitrate reading a around 5. I have been putting fish food in every 12 hours and am noticing alot of fish food on the bottom that is starting to get hairy. Is this normal? Should I get a gravel vaccum? When should I start doing water changes? Do you think it is ok to start adding fish. I do have 3 ghost shrimp in there that have done perfectly fine throughout the cycle.