This is not my first time growing but its my first time indoors with lights and nutes.
I'll give all the information I can. I have 20 plants AK48 and Master kush. The problem seems to be mostly with the master kush. The edges of some of the leaves are dry and curling under. There are also a few 'burnt?' spots on the leaves and one or two are blotchy yellow but not much. There are also two new leaves with yellow tips. Otherwise they are all very green and healthy with good growth.
Now this is what I know I've done wrong.
The temperature has been hard to control because of where they are.
The highest point got to about 30 degrees C when I was getting used to the lights and the lowest it got to was 5-10 degrees C at night because theyre in the basement.
I definitely overfed them in the beginning because i wasnt used to the amounts.
I rinsed them through to wash that out and fed them less.
They are in lite mix topped up with a little peat because I ran out of litemix.
I'm giving them tap water but its not hard water. No lime scale is obvious.

I would appreciate any advice before this problem gets any worse.
pics here
https://www.thctalk.com/gallery/showgallery.php?cat=2219