Ugh, I swear I've read all this, but I'm a learner by doing. Soon, I'll be a professional. Thanks for your help. Again.
I tested every day at first, but it didn't take too long before I could accurately predict the test results before testing, so I backed of to every 2 or 3 days as well. However, when things change, rain, more or less sun, lots of leaves, etc, then I still had to test daily to be sure. That was in the summer. Now in the winter, I can test once or twice a week. In that cold shaded water, things change very slowly.Sounds like you are getting it nicely sorted - once you get the hang of it, you only test every 2 or 3 days and get into a 'holding pattern' - you pretty much know what to add and how much, and make very small adjustments.