You don't need to be accurate. The instructions say to use two dippers but one works fine most of the time. One clue here is thst the instructions say to use two dippers for either the 10ml sample or the 25ml sample.

Just put some in, if the sample turns pink, you've got chlorine.

I just tap the dipper on the top of the test vessel and let the R-870 corner of my kit box get a little messy.