My bad I didn't see your post before the one with pics, but that is a pretty good strategy, people need to learn to do more of what you do with just watching your plants and letting them tell you what they need. Too often people look at different factors to determine if there is a problem and then they go about fixing something that isn't necessarily broken, when really all they need to do is look at the plant to see that it is indeed healthy in the conditions it is in. I do however still like to run all kinds of tests just so I know what is going on incase a plant decides to start looking sickly. It helps me to keep track of changes in conditions so if there is a problem, I can typically tell where/why it started, and easily make the necessary adjustments.