If you have high pure sn both nitrate and nitrite will show high in strip test, I would say if the nitrite is high sn is good to go
If you really want to be sure
Order this strip as they are more accurate and reputable brand when it comes to testing
Dual-pad strips for nitrite (0-25 ppm) and nitrate (0-500 ppm) testing. Ensures accurate water quality assessment.
bartovation.com
Do you see this on your strip holder
View attachment 113068
Basically says if there's any nitrite in the solution, the nitrate reading is useless since it uses the same reaction as said above. (Nitrit is german for Nitrite, it's a typo)