I am using the API test kit and have trouble reading the color charts for the ammonia and ph. Especially when the ammonia is .25.... sometimes wishful thinking makes me think it is 0. Also with the high ph - the purple for 8.4 and 8.8 are so close. Does anyone have a suggestion for what else I could use?
I felt the same way when I started out, but I think you might be trying to micro-micro manage. IMHO, it's not so important to have the EXACT numbers as it is to know what range they're in and compare that to previous readings, and I don't have a problem with guesstimating. For example, I am currently cycling an indoor tank [for a special-needs goldfish that wasn't doing well in the pond....]. My nitrate has been 0.0ppm, but last night it was starting to rise. The chart starts at 0pp, then goes to 5.0, 10.0, etc. There was a color change, almost imperceptible, but it was there. So I guesstimated it as "2." It was >0, but <5. That is now my reference point for the next test.
Now, the GPF experts may disagree, but for a garden pond...... It depends entirely on you.
They do make "meters" and various electronic testing devices, but I can't speak to their accuracy or cost efficiency.