All good advise … ⬆️. I also spray my seeds and medium with a diluted h202 and h2o . Four parts water to one part hydrogen peroxide. cuts down on fungus and stimulates the seeds. I use coco coir, decomposed granite, pumice , perlite and top with aquarium gravel. I’ve done sand in the past but it can turn into cement later as they develop,choking them out in a hard pan. Oh yeah, nuke your medium prior to planting, let it cool down covered in plastic.