Plants drying up at five weeks flower

I should have posted this a year ago when it began. I have been growing in a 5x5 are for a few years. I had pretty good success for being a hobbyist but I’m getting very frustrated now. It seems like ever since ( one year ) I replaced my cheap Chinese lights last year I have had this issue. Here are a few notes to hopefully fix this issue.

5x5 closet
7 gallon smart pots ( no fabric , the plastic ones with the holes )
Growing in coco
Exhaust fan always on
AC duct I’m rooM kicks on when AC unit kicks on
Using a bunch of AN nutes ( I’m a nute junky)
Pictures are at 4.5 weeks in flower
Took down Nextlight mega and now using a light a guy built me ( smaller , so I thought it would be cooler.
Room is tough to keep humidify and temps correct. Watering temp is 68-70F.
tower fan blowing on lower branches. Two other oscillating fans on canopy Temps range from 72-82 and humidify is around 50
Multiple strains growing but they all seem to be doing it although the shortest one seems to be the healthiest. Each get a little over a gallon a day

Since I got these good lights , I almost feel like they are growing too well or too fast. I just don’t think I have changed anything but the light. The last grow basically had no leaves when it came time to harvest. I still got about 10oz each plant dry. Could it be heat stress ?? I have a dimmer switch on the light currently hanging. I was thinking of turning it down but I’m a light junkie too ! Lol Thank you for reading !

looks like nutrient toxicity. the last picture looks real high N. I had the same problem. What are your PPMs?

I’ll be honest. I haven’t checked in a long time. I think I remember it being around 1100 and when I called nute company they said that was ok and it was like they almost said you don’t have to worry about PPMs with their product. The water without nutrients is about 130 I think. I keep my PH around 6. You could be correct about the nutes. I will be the first to admit ,
I do sometimes go over board . I think I may have a problem I can check the PPM tonight and let you know

They always seem to start out with brown tips in the 4/5 week of flower

Phosphorus...
Locked out or under fed.

I Just mixed a batch of nutes. 130PPM out of the filter and 2100 with nutes

EduardoCorochio said:

I Just mixed a batch of nutes. 130PPM out of the filter and 2100 with nutes

Click to expand...

Ouch! Less is more

Your environment seems ok. Not ideal...but workable.
But, your PPMs are way too high causing all kinds of havoc.
Use a balanced base and ditch everything else until you dial that in.

Tangerine_ said:

Your environment seems ok. Not ideal...but workable.
But, your PPMs are way too high causing all kinds of havoc.
Use a balanced base and ditch everything else until you dial that in.

Click to expand...

Thanks Tangerine. I think I figured out what it was. I upgraded my light , kept the same nutrient regimen but didn’t update the size of my pots. I’ve read many places where smart pots ( the ones with the holes made of plastic and not the cloth pots ) can’t get root bound . I don’t think that’s correct. I think they outgrew their pots . I remember the last time this happened I opened the pot and it was solid roots . I’m going to start using 12 gallon pots and see if that makes a difference. Thank you for your response !

2100 is wayyyyy to much ppms

EduardoCorochio said:

I Just mixed a batch of nutes. 130PPM out of the filter and 2100 with nutes

Click to expand...

My guess is way too much nutrients. Run some low ppm water through them to a nice run off and come back and tell us what the run off measures in ppm or ec. Im gona guess its waaay higher than what your putting in and you have salt build up and lock out.

If you're in coco, a 12 gallon pot is not going to solve your issues; it may simply complicate them. Unless you're attempting to grow a literal tree, a 7 gallon pot, let alone a 12 gallon, isn't necessary. If it were me, I'd get a handle on your pH and nutrients. Good luck friend.

EduardoCorochio said:

Using a bunch of AN nutes ( I’m a nute junky)

Click to expand...

Answered your own question.

What was your water before pHing??? @EduardoCorochio you said it was 6. was it way below 6 or way above 6 when you started or is it at a 6 by itself? I had this issue when I was adjusting from seriously acidic water. but it's unavoidable with salt-based pH/nute solutions. I started raising and lowering my pH with white vinegar and Soda.. been doing it for years. I can dial it in a way easier that way and the plants really don't have any issues they love the water lol. my tap water is brutally acidic, its at a 5.5 from the tap. This is what works for me. But everyone is different.

Crazy high ppm, less is more

Best thing I ever did for my grows was start @ 1/4 strength, never getting to full strength until the peak 5-6week of flower if the plant is asking for it.

Personally I dont feed over 700ppm