Bottom set of leaves dying?

5 GHS The Church growing at the moment theyre into their 6th week of veg 18/6 and the bottom set of leaves on 3 out of 5 of the plants have yellowed and some have even died off and fell off.

I did have heat issues early on in veg but theyve been solved now.

Keep my ph around 6

Temps are around 81/82 in the day Humidity is around 40%

Is this normal or do i have a problem ??

Feed them girls if you haven't already

been feeding at the reccommended amounts on my feed chart, should I add a little extra?

yep

if she's eating N from the bottom leaves, feed with some more N

use caution and sense as burning is a whole new can of worms