I have a drop test kit (AquaTrends or something like that). This is probably a really dumb question but here we go.... I have been using it since last summer and I have never been able to get a decent reading on Cl or Ph. The instructions to test Cl are add five drops of yellow bottle 1, 5 drops of yellow bottle 2 then invert once to mix and then match the color to determine the FC level. When I look through the tube, from the side, the color is very pale, even after shocking 3 days straight. But the other day I happened to glance into the tube from the top and the color was very deep purple-ish, which is what I would expect from a high chlorine level. After emptying the tube, I noticed a white disc in the bottom, as if this was to be used as a background for reading the color.

My dumb question is: View the liquid/tube from the top or side to match the color on these tests?

Thanks,
Ed