soilless -- -you fertilize every irrigation with 10% runoff... simple as that. total concentation of a well-balanced feed around 1,3 to 1,5 EC. this doesn't include what your tap adds, so it likely measures higher. 6,0 to 6,2 pH is great. little off either way is okay too.
how much? too many factors at play. depends on your intentions too.
Simple context - you wait for top layer to change color then re-fertigate with 10% runoff (waste). You can determine volume needed if you irrigate at a similar point each time. Feel the weight of the pot. that loss of weight is equal to the amount of water you'll need to add. After your first cycle, you'll have a better idea of how much you need to mix up.
Be religious about that 10% runoff and it is impossible to have a buildup caused by any mineral retention in the substrate. if you feed somethign out of balance, you'll still end up with a toxicty or deficiency. It'll also maintain your substrate pH. The idea is a consistent charge and balance of nutrients that results in best growth rates being ever-present.
frequent fertigations can match hydro growth rates. this takes a bit more familiarity. the size of pots must match rate your plants drink to avoid root rot etc. get a few grows in before tackling that complexity.
