Correct. The pool would be around 1501ppm.
BUT... before adding the 10,000 gallons at 1ppm, the pool contained 10,000 gallons at 3,000ppm. Where did the other 1499ppm go?
You said you DRAINED it???? Only the refill would dilute it
Regardless. As you indicated in your original post, the only way to go from 3200ppm to 4300ppm is by adding 300lbs of salt which could not possibly have come from a couple of gallons of acid (or anything).
So, maybe your original reading of 3200 was before the salt had fully dissolved although salt will usually dissolve within a couple of hours (24 hours max).
My test results were consistent up to two weeks after adding the salt, then I began to see a gradual rise. I've added well over 100 gallons of acid in this time span.
I will admit that when I converted to SWG, I was using the salt test strips incorrectly resulting in a false low reading so I added more salt before realizing the error. I had to do a 40% drain/refill to fix it.
I've had the Taylor test from day one, knew the exact volume of water of my pool, tested prior to adding any salt (600 ppm), and added the correct amount of salt (per pool math) to get me to 3200 ppm (confirmed several days afterward).
Draining and evaporation are completely opposite. There was no mention of draining and refilling until you brought up your example which does not apply to this situation.