Aloha Zeroturn!
Here's what you need to know...the key to easy interpretation of the pH color test is to get the proper ratio of test sample to drops (the directions don't always help you to reach this ratio). The COLOR (frequency--going from a neutral yellow-orange up to a bright magenta) of the sample is dependent upon the pH--the color will not vary if you add more or less water to it--only the SATURATION of that color will change. If your test sample is DARKER than the plastic comparator colors, simply add some water to your sample and see how much easier it is to find the right match. If your sample is too LIGHT, add one drop of the Phenol Red and see if it gets easier to compare.
As Dave said, time and experience will help you to figure this out...but it becomes really easy once you learn to get the right amount of drops. I often use a small sample (the amount doesn't really matter that much) and only one or two drops to get the right ratio. And I really don't even need the comparator any more...I can look from across the pool and tell if it is 7.4 or 7.6, as long as the SATURATION of the color is properly reached.
Hope this helps!
Aloha!