New Soil Run off PPM High

it's certainly normal, there's fertilization for 5 weeks. I don't know that product because it doesn't exist in Italy, but there are soils that are pre-fertilized for 5 weeks, and if you need to use them to germinate a plant, you need to do a thorough flush and then plant. Anyway, by watering, you tend to transport the substances down where the roots haven't reached yet, plus it's organic, so the plant, with the mycorrhizae, absorbs what it needs.