You can’t pH adjust distilled or reverse osmosis water the readings will be false. There isn’t enough conductivity. Flush with pH’d tap water until you correct pH and then feed right after. It will be a LOT of water in soil. I’d bet 30 gallons. Flushing with distilled or RO will just flush the nutrients out will not correct pH, because it will take on the pH of the medium.
Use cal-mag prior to any other nutrients you are running. I’m not familiar with the line so maybe someone else will comment.
It also looks like you are already getting support in a pre existing topic…