Did my fish tank just totally cycle in 2 days?!? Is that possible? I have a 10 gal tank I want as a Betta tank. I added a filter from one of my established tanks with established media pad in it, added tetra safe start beneficial bacteria and a zebra danio 2 days ago.Last night my perimeters were ammonia .25, nitrite .25 and nitrate 10 ppm. This morning it's ammonia 0 nitrite 0 and nitrate 10 ppm. It appears to have cycled, but never saw a tank cycle in 2 days. Is it possible to have already cycled that fast?