Generally, you are correct!!! There is a saying around here, don't be a slave to the machine. That means understand what you are doing don't just do what Pool Math says. It is a guide and a tool.
Let's start with pH. 7.6-7.8 is a recommended target. Don't know why pool math would give you a recommendation to lower your 7.5 with acid. Maybe that was a recommendation to lower your TA...see next paragraph. Generally, If your pH starts with a 7, you don't need to do something to change it.
As for TA, it will come down over time, really no need to do anything at TA 100. pH will normally rise by itself. When it gets to 8 add muriatic to get to 7.4 or so. When you add the Muriatic, it will lower TA. pH will rise again naturally without raising TA. At some point your TA will be low enough that your pH will stabilize or stop rising. No need to chase TA at the moment. Just manage pH in the 7s.
You only test CYA at the lines. Fill to one line, obscured? No, fill to next line. First line it is obscured you are done. That is your CYA Do the test, when you are outside with bright sun at your back and tube at your waste, use a glance to see if dot is there, don't stare. Your CYA is 50 for pool math purposes.
Get 50 CYA into Pool Math, your target FC should be 6-8 (found here -->
FC/CYA Levels). FC at 9.5 is fine, it too will come down. As a new pool user don't ever let your FC go below 5. You will learn what your pool needs on a daily basis. Why don't you test as early in the morning as you can, then again after sundown tomorrow. That will give you a read on your daily FC demand. Let's say you use 4ppm. You will then want to redose chlorine to 9 FC daily. It will use 4 and you will end up at 5, keeping you above minimum and avoiding algae.
Hope all this helps! Contrats on the test kit!
Post up some pictures of the pool, love to see it!
