It’s damping-off time again, that dreaded fungal disease that topples seedlings at the soil line. Solutions presented here and other places include watering with chamomille tea, powdering with cinnamon, even using hydrogen peroxide. One very popular book (bible) on organic vegetable gardening recommends with a straight face that you sterilize your containers and use sterilized seed-starting mix, then water with compost tea (bye-bye sterility).
The fact is, damp, cool conditions awaken most of the fungii that cause damping-off, so bottom water and keep the soil surface reasonably dry. An oscillating fan set on low not only keeps things nicely dry, but activates the hormone that makes seedlings more stocky and sturdy (it mimics breezes in the outdoors.).
As to the potting mix, we’ve included compost in ours for years, top-watered tens of thousands of seedlings in our greenhouses, allowed the soil to dry before waterings, and virtually never lost a plant to damping-off.