Hi Lazuli , Ripen is a PK booster, so you're right that you should stop using it before the flush , PK boosters if they are not properly flushed can make a strong and harsh taste . I flush a minimum of two weeks plain water no run off, but often i go three weeks. You're okay with one week in coco, two in soil , and a few days in hydro. Hope this helps ! 🚀