My poor ganja =( leaves turning yellow and drying on the tips

Hey guys i need some help pretty please with sugar on top xD
In a greenhouse (sunlight) in pots i have 40 or 50 plants. They have all started to flower in the past 2 weeks. Some of them are doing quite good but some plants leaves are yellowing and drying on the ends and eventually falling off. Some are in slightly small pots but i dont think thats the issue. Its 28-30 degrees and im watering them with tap water. Its PH is around 7-8. I was adding distilled vinegar to drop the PH to 6.5. Should i water them with drinking water? I was also foliar feeding them with a full spectrum nute and giving them nutes in water once a week. I have stopped doing that now. What could be thiss problem? I added some pics too some of the buds =)

those look amazing. those tips are burnt.. but usually the plant yellows out when its flowering

Hmmm they are losing their leaves pretty quickly for it to be natural. Some are curling upwards at the tips. Can this be any kind of shock? Im not watering them with drinking water with a ph of 7.2 i thought there may be less EC in drinking water. What do u guys think? peeeeeeaceee

i think your post shouldnt of been pot on plant problems thats for sure