Auto grow Variety Pack for Newbie

The one aspect I’ve avoided learning or checking is soil pH. I’ve pH’d my water and nutrients and hoped that was enough. It wasn’t. My prize plant which has been so robust started showing stress and yellow scoring on leaves. My soil pH meter said 7-8. I flushed with a gallon of vinegar water at 5.1pH. The run off was 5.9. I hope that I acted correctly and timely. Fingers crossed. Time to check the other ladies.