Did you run a diluted CYA test or was the sample somewhere between the bottom of the tester and the 100 mark? The test only goes reliably to 100. If it's higher than 100, it may be A LOT higher. The diluted test (with 50/50 pool water and tap water) will give you a much better ball park figure of where you're at.
I did not run a diluted test, but I understand what you're saying and I'll probably do that instead. My mark was well below the 100 mark. However, the test strips said I was at 150 so I assumed the number was somewhere around there.
- - - Updated - - -
Sounds like you're in the right track
I'd suggesting finding articles on how to drain a vinyl pool safely so the liner doesn't get moved out of place, it's going to need multiple small drains or a very detailed large drain :/
Yea putting together a list of my best vinyl drain options now. Need to be careful here. Thank you!