Is this a Magnesium Deficiency?

so it started a while ago but only lasted a short time, and went a way for a bit. check on it today, and it has progressed badly and i am starting to get concerned. treated it with epsom a few days ago, bout a half tsp to a 28oz spray bottle, applied as 3-4 solid foliar sprays. should i go for a stronger treatment or perhaps is this something else?

heat stress

i dont know how that would be possible, the temps rarely get above 78 or so. i would say they average 73-76 ambient temp, and around 75-80 radiant temp

any other ideas? iam in the middle of a flush in case it truly is a nute burn....

i know someone out there has seen this before. just tell me whether its burn or deficiency! haha this is what i get for not just using FFOF like everyone says to

Ive seen this on a few of my plants and I usually fuck around with my nutrition balance and maybe give a little extra water. Shit, a lot of times I just ignore shit like this and eventually the bitch well snap out of it.

well that's what i went with when it first showed up, and it seemed to be going away. a 2 day break from the place, i come back to it like this, and it has only gotten worse since then. ill have a new pic up tonight when lights go back on but its not lookin good, if it doesn't perk up i fear ill lose her before i even have a chance to fix her (running on a tight work schedule at the moment and UNFORTUNATELY that has to take precedence over my mj)

shameless bump for the sake of trying to catch a few night owls. heres a fresh picture, like i said has gotten much worse, hopeing i dont just lose the whole plant.
heres a pic of 2 plants. one on the left is obviously the one with the issue. the other one is same strain, soil, temps, ferts, everything.

the leaf cuppin is usually from heat stress, what kind of lights are u using? and how close are ur lights?

I would not say that is a Mg deficiency. Have you seen this:

https://www.rollitup.org/general-marijuana-growing/1469-marijuana-plant-problems-cures.html

Mg is photo # 15 and that is not what is going on there, so keep looking.

Whats your PH soil and water. What are you using for fert. JR

the temps rarely get above 78 or so. i would say they average 73-76 ambient temp, and around 75-80 radiant temp. i thought heat at first as well, but again this plant is just as far away from the lights as the other 2 are, and they aren't showing the same symptoms. the light is about 8 inches away from the pants at this point i would say. they are T5HO fluoros, puttin' out about 25k lumens. Ferts are FF Big Bloom at a ratio of about 1 teaspoon or 2 per gallon of water (ive been keeping the ferts light, havnt shown any need of any until these symptoms and didnt want to risk making it worse since i wasn't sure what it was)

-edit- sorry forgot to add the pH. the water is tap, ph'downed to about 6.5 ish. as for the soil i have no real way to check, as far as i can go is check my runoff, and that has been tested and shown to be on average around 6. i wish i could be more accurate but iam stuck using a color coded aquarium 'droplet' kit to test until i can afford a better alternative.

startin to think maybe the best option is to go get that FFOF tomorrow and just transplant her, hope for the best.... been searching the web and Mg deficiency is about as close as i can seem to find, and i could only assume the only reason i am not seeing any results is because the Mg is being locked out by some unknown (to me) variable.

I think mine have a magnesium deficiency and it does not seem to conform to what is happening to you at all.

Magnesium starts on the lower leaves and works its way up and results in drooping leaves with dead edges.

Your issue seems to be at the top leaves with curling and such and then a burn at the base of the larger leaves below which I have no experience with.

You are doing the right things though. Flush, replant, water with proper nutes...

well i do believe your right. early on i thought it may have been hotspots in the soil, but in essence its the same idea, i think a combo of bad ph to start with and then not being able to ph my water until a week ago, and even then it was with the drop tester. as for testing the nutes ive been able to test them within reason, because the amount of fert ive been adding to the water was barely enough to change the tint when fully mixed, so i the drops still worked.

all in all, when i first posted this problem a week ago on a different thread, i was asking if it was ph, and ya, iam starting to think more and more that it is. ill transplant here as soon as i can, then ill be attempting to invest in a soil/water ph meter.

oh and fantastic call on the humidity. my RH is usually quite low, like 15%. even with a humidifier i was only able to bump it to the low 20's, but that humidifier is a piece of shit, so ill work on that as well. thanks again for the input!

dont take this as a confirmed solution though, always willing to take some tips from as many people as possible, and thanks again everyone for your time to advise me!

Humidity is an easy fix KK, just run the SMALLEST humidifier you can get ahold of. Couple hours a day will do wonders for them. Use distilled in the humidifier and watch the moisture around your electrical gear. You caught it early and they are young. I would get a good meter and you will be surprised how often you use it! Good luck and please post an update, we will get it figured out! Start with a good flush! Wash out all that built up junk out of the soil and no more nutes for at least a few weeks...

next nute already on hold til i can ascertain a positive deficiency later (i.e. not until i know for sure it needs it). as for the flush, did that about 2 nights ago, flushed til i had a decent amount of runoff (this was the second flush in a week and a half so i didn't go the full 3 times the soil, more like 2x) and the soil i still pretty saturated from it, so we'll see how much it helped.

as for a soil/water kit, have anything in mind you would recommend? been lookin online and i figure i may as well do it right, and i can only find mostly cheap stuff. cheap is ok if it will get the job done right, but i didn't want to drop 20 bucks on something i would find out i need to replace in a week.

the humidity is on my list as well, iam going to get a $15 vicks humidifier tonight, since i think the one iam using is broken somehow and i'm not even sure how (seems like its missing a heating element or something, the fan spins but there is no mist, and it takes DAYS to use a tank, rather than a night which is what i remember needing to do with my old one). my only question is, this is in a closet, and not fully sealed in anyway. will it still do ok to humidify it? or should i finally take the plunge and look into a way to seal it off (thinking velcroed mylar or panda film).

and thanks again for the help bud, i have a pretty damn good grasp on most things growing, but iam still picking up the little things day by day, so you could see why at first i had diagnosed this as a deficiency.

hey thanks for the reply. ya for sure though, on page one i covered that. my nutes have been VERY VERY low when used, and even then only used twice in the month since germination.

i tried the epsom treatment to no avail. good news is the girlfriend is bringin home a cheap humidifier (my area is VERY dry). gunna set that up, and just hope that in the next 2 weeks, it doesnt keep progressing.

in the end its gunna be ok, this was a trial run for a reason, and ive learned alot already from this lol

-update-

so i put a humidifier in the closet today. brought the RH from an average of 15-20 up to a stable 40, and holding strong. this seem like it should be enough? or should i be finding a better humidifier?

new top leaves emerging aren't showing any signs of damage, but if they are anything like the other ones, they wont until they are about 3-4 inches wide, then it will start....