“ramping off at the soil line” - what is that?
Damping off happens when the starter soil becomes too wet at the surface. This can happen by over spritzing or just too much watering. The grit is super dry and prevents the “rot” that kills normal seedlings.
Also remember, don’t over do the fish fertilizer on baby plants. The tops will do just fine. Look for a fertilizer with potassium to boost root growth. At the early stage, root development is important.