It looks like very fine icing sugar to me? It's white and on most of my seedling soil. I'm curious if it's something to do with the water I use?
[img]https://imagehost.vendio.com/bin/imageserver.x/00000000/valuemet/seedlingdec1.jpg[/img]
Looks like low solubility calcium salts (calcium sulfate, calcium carbonate, et al.) Generally from hard water. Nothing to worry about.
Common after adding epsoms salts (magnesium sulfate) because calcium grabs onto the sulfate. That is one reason you don't want to add epsoms salts to your fertilizer, and instead give the epsom's salts on a week you don't fertilize.
Common after adding epsoms salts (magnesium sulfate) because calcium grabs onto the sulfate. That is one reason you don't want to add epsoms salts to your fertilizer, and instead give the epsom's salts on a week you don't fertilize.