Just to put it out there, at petco you need to bring back the fish, water sample, and receipt. Testing the water is supposedly for the customers benefit. It doesn't determine whether or not the customer gets a refund/exchange. Its stupid and majority of the time people bring in the water with fish in it. But its also the most misunderstood concept because what is there to test for? In most cases the tank is brand new and it doesnt take a test to tell you the cycle process, where the high levels are going to be there with these overstocked, thoughtlessly made tanks.