nitrate test kits (seachem and red sea)
 

Just finished testing for nitrate in my tanks with both test kits
Seachem (color chart) reads 20 ppm+ their reference solution shows 10
ppm. Red Sea shows 0 ppm. What gives? Anybody else able to compare
these 2 kits. At this point I'm more inclined to believe the Seachem
results since I'm dosing KNO3 at 3 ppm when I should actually be doing
water changes only and get my level down to 10 ppm or so.