My girlfriend and I both got a betta of our own about a month an a half ago. Two identical 2.5 gallon tanks, same gravel, same artificial plant types, they have been receiving the same food, etc.
My GFs tank water has been perfect ever since we started using test strips, and my tank water was perfect for a while, but then I noticed the nitrIte was getting into the 1-3 ppm level. I am using API Stress Zyme and Stress Coat and am doing weekly 40% or so water changes. I have some API aquarium salt I put in as well. I just can't figure out why I keep getting high nitrite in one and not the other?