I am a big fan of the ACV--- It has been a miracle for me & my little chicks (and big ones!)
Start with electrolytes or ACV, either way. Hopefully your new chicks are healthy to begin with, so the extra nourishment isn't a dire situation.
What has worked for me, is making a special mash once they are a week old. I take a little bit of ACV (I like Braggs with "the mother" you get it at health food stores) mixed with water, and add a tiny bit of molasses until it looks like iced tea color (I have stopped measuring since I do it so often now) Then I cut up cardboard egg cups, put some chick starter crumbles in and pour the liquid over it, making a mash. Once a day I drop the egg cup in there along with their regular dry food & they go crazy for it. Then I just take the egg cup out when it's empty & place it in the compost--- no dish washing necessary.
My boyfriend calls it "monster mash" since they go crazy for it & grow up to be big, strong little monsters! I haven't had a single problem with pasty butt or vitamin deficiency since I've started incorporating the mash. I even give it to my hens when they seem sluggish.
Just my 2 cents...