what's going on?? help needed please folks

i just got given 3 og kush plants 3 weeks into veg looking very healthy when i got them, i put them on 18/6 and followed the canna grow feed calc (using canna nutes) coco soil, in 10ltr pots, a few of the top leaves had shrivelld up and look dead should i remove ? i moved the light futher away and added a fan aswell as my extractor fan, most leafs look and feel healthy with the odd yellow tip on one or two. i am new to this and would appreciate any input anyone has. any1 got any pics of og kush to compare, no camera guys sorry!

if the leaf is not green or light green/yellow then you can remove it if you want, yellow tips = nute burn if i had to guess back off the feeding to 50% strength if your not already

im guessing your pots are going to be small for your plants, my plnats veg from 4 to 6 weeks and i use 5 gallon pots, as for the leaves i have to go with m27...nute burn, and depending on the light, which im assuming your not using anything big so it shouldnt really be a problem...by the way, what kinda lights are u using....for quality buds you will want to use a 600 watt or higher depending on space and amount of plants.....it will make alot more nugs...