HELP! Leaf Problems Spreading Slightly

[Trimmings426]

Hey there friends. I posted this same thing a week or so ago and things has not cleared up as of now. I'm getting worried cause it's beginning to get close to my harvest time in bout another 3 or 4 weeks. Tomorrow my ladies are starting in their 6th week of flower and I've got to get this problem fixed ASAP. I've got some new pics to show of the affected areas and leaves and they have gotten worse and more.
First let me give a run down of my growing process as to assist you in assisting me.
Grow Area Closet Grow 5ft.X2.5ft.X7ft
Lights 600 watt MH for veg 600 watt HPS for flowering
Pots 3 gal. Fiber Pots
Medium Fox Farm Happy Frog For Seedlings Fox Farm Ocean Forest For Transplant
Air Movement 2 8 inch oscilateing fans On Floor Faceing Up At Base of Canopy 1 12 inch oscilateing fan blowing over top of canopy (good air movement and breeze going 24/7)
Exhaust 410 cfm inline exhaust fan vented through ceiling and 410 cfm compatable carbon scrubber
RH LIghts ON 28-30 %
RH Lights Off 35_40 %
Feeding Schedule & Type Of Water Used For Feeding Water every 3rd day useing the pot lift test water when pots are very light like a feather
Nutrients Fox Farm Organic Soil Trio (Big Bloom, Grow Big, Tiger Bloom) 1/2 strength till bout 3 weeks ago started useing full strength
G.H. CalaMagic 1 tsp. as recommended
G.H. Armour Si (Silica) 1/2 tsp as recommended

I tested my temp. with the door shut and the over all temp with lights on stays about a steady 90* F just above the 86* F point that is stated to be ok during flowering but some of the damage looks like heat stress but also kinda looks like calcium or boron def. so like I said I'm stuck and cannot figure it out nor fix so if you can assist me it would be greatly appreciated.
Also the brown tips and edges on the leaves end up crumbling away and falling off like their burnt so again seems like heat related only its not only on the tops and the buds are not effected yet but thats what I'm worried about.
Ok heres the pics and thank you all in advance for your help.

[KTM690]

Great looking buds and your set up is sweet. Only things that pop out to me are those temps and full strength nutes. Didn't see anything about you ph ranges. At 3 to 4 weeks till harvest a flush could help some and lower temps for sure I don't like anything over 82 really like it at 80 or lower

[Weed Pharma]

First and foremost- you will make it to harvest !

Watering the method you are using, is fine for vegetative grow- but you do not want to hold back water during the bloom phase. Water every 2 days.
I'm not a fan of routine flushing as it stresses the plant- but in this case, I would do it and then reduce the feedings to weekly, at the lower strength for 1-2 more weeks.

Old damage will not repair itself and the plants metabolism has slowed down at this point of the grow and therefore does not need much nutrients- if any.

As mentioned above - keep your temps under 80f and decrease the amount of airflow over the top of the canopy.
Increase your light distance (or dim it-up to 50%), as the slower metabolism doesn't require as much light at this stage of the grow. (think fall shorter days, less sunlight, cooler nights).

[alltatup]

Hi Trimmings, I totally agree w/ KTM: temp's way too high for flower, when it should be closer to 70 degrees, never above 80. You risk heat stress and possible hermies appearing--not to mention all the good chemicals that are evaporating at those high temperatures.

What's the pH been?

What did you do in the past week to remedy the problem?

[Trimmings426]

Well as in my journal I do a routine flush every 4 weeks with Fox Farm Sledge Hammer combined with Fox Farm Boomerang, my pH levels got a bit on the high end starting about 3 weeks ago levels were at around 6.8 and 6.9 but still in the range slightly. when this occured I started useing some pH down with my feedings and makeing the feeding solution pH at 5.8, 5.9 and was checking the run off every feeding and by the way I check run off every time I feed just to make sure things are where they should be. Ok after lowering pH of feeding solution the run off was at 6.3, 6.5 for both plants. Now jump to the last feeding time which was Sunday night at lights on, Ph of solution was at 6.4, 6.5 without pH down so I used this to feed them both and when I checked the run off it was at 6.9, 7.0 on both plants so the pH is still a bit to high. I thought during flowering you should blast the lights and give flowering plants as much as they can handle without hurting them but its the exact opposite?
So it'll be good to lower the light to 50% or 75% and reduce the heat that way and my yeilds will still be good without all that bright light is what ya'll are telling me then right?

[alltatup]

Trimmings, I don't know about "blasting the light" during flowering; I said the temp is too high. You want to mimic fall conditions, especially in the second half of flowering--cooler temps especially.

This may help with your lights and at what distance from plants they should be: https://www.growweedeasy.com/how-far-grow-lights