Indoor Over watering?Burn?or deficiency? or something else

[Noreaster]

3 Bubba Kush HSO autoflowers aged 34 days
Indoor grow 1500W blurple(251draw) @ 18-24inches
Watering usually every 3-4 days with ~2L water when pots are light
Medium is Sunshine Mix#4 aggregate plus
Been Phing 6.5 in runoff was showing 6ph
2 pre flowering 1 flowering since last week
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Growth seems stalled slightly.. leaves looking somewhat droopy. Each plant slightly different. Seeing Yellowing, browning spots/tips on lower growth.. tp growth looked like nute burn, but the yellowing seems to clear up mostly on top as they grow out.. need some advice? Over watering? Nute burn? Nute deficiency? Started with 1/8 nutes Green planet medi one 4-4-3 3 weeks ago, last feeding i went 1/4 strength. I have the bloom nutrients but havnt used yet.. GP Massive. Please help me understand whats happening before i move to correct. Thanks in advance peeps!

 

[namvet25]

They don.look that bad but I would go half dose of veg nutes until flower get larger.Also use cal/mag evert other watering..

 

[Mañ'O'Green]

What are your environmental conditions? Too low or high RH can cause this look. The first plant looks hungry but once again if the stomata are closing the plant cannot transport needed nutrients and in the effort to get the nutrients into the plant the leaves get heavy with water not able to transpire.

 

[Noreaster]

What are your environmental conditions? Too low or high RH can cause this look. The first plant looks hungry but once again if the stomata are closing the plant cannot transport needed nutrients and in the effort to get the nutrients into the plant the leaves get heavy with water not able to transpire.

Humidy hovers around 40 constantly.. lights out sometimes low 50's but very rare ever approach 60rh(just now 40).. temps 23-27C(80), lights on usually 26-27(76-80). 6 inch clip fan, tower oscillating fan on low, 190CFM 4" exhaust to outdoor through a dryer vent. all that seems reasonable i think?

 

[Mañ'O'Green]

Humidy hovers around 40 constantly.. lights out sometimes low 50's but very rare ever approach 60rh(just now 40).. temps 23-27C(80), lights on usually 26-27(76-80). 6 inch clip fan, tower oscillating fan on low, 190CFM 4" exhaust to outdoor through a dryer vent. all that seems reasonable i think?

Your RH is too low for the temperatures you are running. You are in the danger zone.

 

[Noreaster]

Your RH is too low for the temperatures you are running. You are in the danger zone.

Omg.. i didnt notice the change as the environment changed from summer to fall.. a month ago i was sitting at 60 usually.. now its gotten drier outside(East coast Canada).. Thank you for pointing this out.. you are a genius for your insight I have moved my lil humidifier inside the tent, opened a flap for more air.. now i am hoping i can get a speed controller for my exhaust fan. Hopefully i can do it without needing the controller