Did LST today
Watered one with half tsp Cal Mag in 1 gallon water and rice vinegar to change to the pH 6.3
Runoff was in the 5's, so flushed it in bathtub to try to get pH to 6-7 range. Did the recommended double amount of water as pot gallon size - pH range eventually got to 5.8-6
Didn't water the second plant, runoff was still in high 5's.
Looked up Fox Farm soil, looks like a lot of people have this issue too. Just going to monitor and make sure not to add nutrients too early