So, I started a 20l nano tank last month. Brand new bogwood, new substrate, tissue culture plants. Filter media is brand new and not seeded from another tank. So where have the copepods come from that are swimming about in my tank? I only noticed them today, but there are many. And what do they mean? Are they are good or bad sign? Currently no livestock in the tank, but was going to add some cherry shrimp in the next few weeks.