So this is the first time I'm trying to use the 3-step method in my 390 gallon hot tub. I have the TF-100 test kit.
Added brand new water, pH/TA was 7.5/220 which is normal; so I added Sodium Hydrogen Sulfate ~14oz and now my pH/TA is 6.8/110.
I am still going to get my pH back to 7.5ish, but...