First inside grow

Gave the second set of nutes to the autos this week. Pleased with the growth rate on all but the Short Rider #2 (it's got a gnarly looking first set of leaves so I'm not holding out hope for it) and the White Widow #2 (it's finally coming on but is a shrimp compared to its bigger sister). 3 or 4 of the girls have light brown, almost white on the very tips of a couple of their leaves. Not sure if it's a calmag deficiency or some kind of nutrient burn or what. Anybody with some insight on what it could be please comment. I'd like to nip that right off the bat if i can figure out what's causing it. I am very happy with the growth rate on 8 of the 12 girls though and i think 3 of the other 4 are coming around, they're just a week behind the others. One other thing I'd like some feedback on if somebody knows, should i just top that short Rider auto #2 once it starts growing a couple regular looking sets of leaves, if it ever does? I know a lot of people say not to top an auto, and i honestly don't plan to top any of the others, even my photo-periods, I'm just going to LST the shit out of them as they go, but if topping that one help down the road I'm open for it.