[Gooberfish]

So my tank has been set up for almost a week and here are the readings:

pH: 7.3-7.5ish

Nitrite: 0ppm
Ammonia 0ppm

Don't have a Nitrate test kit how badly do I need one?

Also, since the bad stuff is at 0ppm is it still necessary to do a 50% water change? (No EI dosing just excel).

This tank is my 20g in my sig