low nitrates

I set up my 30g tank 3 weeks ago. I was advised to use a hardy fish as an ammonia source so I got a young bn pleco 12 days later. Although I learned afterwards that it's a bit controversial he seems to be well with good energy and appetite. Using a Sera liquid test kit 5 days ago the results...

As title says, I am wondering if/when I NEED to do water changes on my tank? I am not new, I'm well aware of nitrogen cycle, had one tank 7 months, second tank 4 months, both with healthy fish. Been frequenting forums for months, with multiple threads if you care to check my profile, and I've...