My tap water is set by the water bureau to be 8.2. I don't bother to pH in soil. That includes FFOF. I've never had any issue. I only pH when growing in coco. If you do pH do it after adding nutes.
"Portland's water is currently treated to be at a pH of 8.2. The pH of Portland's water can vary by a small amount in the distribution system, but it generally ranges from about 7.4 to 8.4, with a median value of 7.8 to 8.1"