Question on how to match color on drop test kit

[waterbear]

When I look through the tube, from the side, the color is very pale, even after shocking 3 days straight.
Ed

DPD tests will bleach out at shock levels and appear to read very low when the chlorine levels are high. This is one of their biggest drawbacks and one of the reasons I personally prefer the FAS-DPD titration test for chlorine.

[CelticDaddio]

So, it appears my kit does the DPD test, rather than the FAS-DPD?

Ed

DPD tests will bleach out at shock levels and appear to read very low when the chlorine levels are high. This is one of their biggest drawbacks and one of the reasons I personally prefer the FAS-DPD titration test for chlorine.

[waterbear]

Yes, DPD is a color matching test where you match different shades of red to a color comparator, FAS-DPD is a titiration test where you add drops until the sample turns from red to colorless.

[tenax]

+ on the idea of looking against a white background instead of the sky, etc. i accidentally did that this morning when i had the test kit sitting on a white melamine shelf and thought wow..i can really see the differences in colors now

[JJParrish]

Well, in Ben's kit he has some instructions that read:
" Note: for OTO & ph testing, use white inside label as background."

[tenax]

i'm a po' poolboy..test kit from local hardware store what instructions?