What the roots sit in, and what that choice costs you later. Peat-based mixes, coco coir, mineral wool, perlite and the inert media used in recirculating systems, compared by how they hold water and air rather than by the label on the bag.
The substrate decides irrigation frequency, buffering capacity and how forgiving a mistake is. It is the reason the same feed chart gives different results in two rooms, which makes this board a prerequisite for most of the Fertilizers threads rather than a side topic.
Two things come up in nearly every thread. Coco coir arrives with an ion exchange history and usually needs buffering and a calcium and magnesium supply from the first watering, while a peat-based mix already carries a nutrient charge that changes what you feed in the first fortnight. And container volume and media structure together set the wet-dry cycle: the same medium in a larger pot is, practically speaking, a different medium.
The board is new and carries one reference article so far.
Where to start
Related elsewhere on the forum: Organic vs Synthetic Nutrition: Living Soil & No-Till and pH & EC: The Nutritional Foundation Every Grower Needs to Know, both in Fertilizers.