Indoor Sick flowering auto need advice

[hugrem]

I need some advise , this is my first grow in my 4x4 , never had issue like this in my 2x4 , I have 4 auto flowering and all leaves are starting to dry out and die , some are also yellowing only on top , im using about 650-700 true watt of cob light , feedinh using lucas formulas at 1/2 (always did that) , it get a little hot some time (29-30 degree) , I have an intake and exhaust fan , and a little fan to blow on the plant. Any tips or advice that can help would be nice im even willing to pay if u can help resolve this lol and sorry for my shitty english.
Problem: slow bud growth , drying leaves and yellowing top

Medium/grow method: 100% canna coco

Feed: and supplements used: lucas formulas 1/2 strenght

water source: tap water phd

Strain/age: ak47 and gorilla glue

light used: 700 true watt cob

climate :indoor 28-30 degree 40% humidity

Additional info:

 

[Jackson]

I don’t see ph readings. Incredibly important

 

[hugrem]

Ph in 6.3 ph out about 5.7-5.9

 

[Olderfart]

Looks to me that your soil pH may be low. If pH out is that low after pH in of 6.3, pH in your medium may be a bit out of bounds on the low side. Absent contrary advice from someone with more experience, I suggest flushing with the same nute mix pHed at ~6.1 until the pH out is up to to at least 6.0. I just went through this with an outdoor plant I have going, and the flush sorted my problem. My flush of a ~4gal fabric pot took multiple gallons of nute mix to get pH out sorted. I elected to recycle the runoff back into my reservoir rather than waste it.

I am curious about what is causing your pH to drop. With Megacrop and coco, I find pH in both the reservoir and coco go up, not down. But I use plain brick coco that I buffer myself, so maybe Canna Coco has other stuff in it.

 

[Silver]

I would be checking the EC (although I understand your feeding regime is unchanged), if she's being overfed (EC Range higher than what's being fed) that can cause the PH to be lower than what's being given, worth a check.