Dots on one leaf

That white stuff isn't moving is it? get your loupe out to check if you don't know the source. all sorts of stuff can fall on a leaf and just needs a little brush, of course. if isolated and a compelte feed, i wouldn't worry about it. If your feed has cartoon graphics on the lable and requires a bunch of supplemental prodcuts, only god knows. :) But, that looks like a young plant and blemishes are not unusual. Give it time.. .do make sure no pests crawling on underside and those lil white dots.. Are the leaves only droopey after a watering? May need the lights a tad further away while roots expand to intake enough nutrients to warrant the amount of light received. they should be "praying" to the light. I'm currently adjusting to new lights. I have slowly been approaching the right amount of light over 16 hours to avoid major droop the last few (and some major light burn the first day, lol). A younger plant has a lower DLI. Just takes some trial and error.. and time. If i ran them 18hrs it'd need to be a bit weaker yet (further away or voltage lowered).