which nitrate test kit is the best??

I've been having a really hard time trying to decipher my NutraFin nitrate
test kit results. The color chart is basically a light to dark hue of
purple...the water in my test tube looks more like a fuschia/pink bright
color which doesn't match anything. I usually pull the test tube back a few
inches and the hue changes color and I guess.

I've noticed that Tetra has a kit that I might like better; it has a color
chart that has different color shades from yellow to orange to red. This
might be easier to read.

Any opinions?

Thanx a lot!!!!!!!!!!!!!!!
Dave