Alainn

I would use an API master test kit instead of the strips. It's quite a bit more accurate. You can also combat the nitrates with water changes. I read that you're doing 25-30% weekly? https://aqadvisor.com/ use this site, put all your fish and tank/filter information. It might tell you that you need say... a 40% weekly change instead or possibly a different filter based on how many fish you have.