If you seed it with tigger pods, for example, they will reproduce much faster than if you don't seed at all. For $20 for a little bottle, it's up to you to decide if it's worth it. I just bought a bottle of live rotifers from ebay for $10 shipped, I hope those will work out well in my fuge. I don't know how different those are from tigger pods, I just know they're really tiny, not like copepods, which get fairly large.