So I started a 20 Gallon long fish tank back on January 8th, almost 3 weeks ago.

I started off with a fish-in cycle, and I had 2 corydoras in there on day 1. And about a week later, I added 5 Pristella Tetras and a Betta.

I tested my water this morning and much to my surprise (ammo-0/nitrite-0/nitrate-0)

How after 3 weeks can all 3 readings be zero?