I think it might that I have them in a closet and it gets pretty hot with the lights but I tried using a fan but its still getting worse I think I need to make a way for the fan to be more effective
From what i read on fertalizers, this can be a sign of too much fertalizer usage, the salts can block probber uptake of nitrogen and some other needed nutrients making leaves go yellow from the bottom and up. Growth period of cannabis (Vegetative growth) | Blog Philosopher Seeds Nurtient part has this info here
Take a pic of the full plant, please. How often do you water? When you water, how often if at all or how much nutrients do you use. Also what soil do you use?
If he's getting 6 pH isn't making his leaves look like that. 6 is low but not low enough for that. I actually have my germ and seedling mist pH at 5.8 their first watering is 5.8 and gradually raise pH to 6.5 at about mid veg is when I'll reach 6.5. may not be how many do it but that's how I know 6 is low but fine. He has a deficiency or root issue, just not enough information to make a judgement on.
All the burns start at the tip and seem to only be effecting lower older leaves bad nute burn, process of elimination with more info lol almost looks like a bad over watering as well the dropping dying but still healthy leaves even the dying leaf was reaching with what it had left
I water around once daily, ive only fed it once with a bit of bonemeal, I was trying to get it healthy again so I could transplant it into a bigger pot with some better soil. Im not really sure where I got the dirt
Overwatering. After I transplant my plants into five gallon pots I don’t water for about 5-6 days. They absolutely do not need to be watered every day. That can cause multiple issues. The dead looking spots on the leaves look like it could be a number of things. Also what soil are you using? It needs to be aerated with perlite, which will help with overwatering. How old is your plant? What nutrients are you using? You said your having heat issues, what are your temps and humidity. You plant can still bounce back. These plant are tougher than people think. You just need to get more dialed in. Hope that helps! Had to fill in some blanks. Plant Doctor - Diagnose Your Plants! | Grow Weed Easy
So over watering isn't watering too much at one time, over watering is caused by watering too often. When you water do you water enough to allow about 20% of what you put in to come out? The dropping and dying leaves are signs of over watering. Even in starter half gallon pots I water every 3 days the 5 gallon air pots I water every 3 to 4 days. Even starter single cups are 3 days. My first plant I watered daily, and almost killed it, had to remove the plant from its current soil. Held the plant stem with root in hand, to clear the caked up mud off it's roots then replanted it. You can remove any dying leaves and need to but if you've been watering every day I would almost bet the plants are pushing root rot. Let your soil dry or transplant. Let your soil dry out before I water my plants have to pass 3 questions. Feel,look,and touch. I pick up my pot right after watering to feel how heavy it is, when I think they are ready for water I pick it up again, does it feel light. I'll look does the soil appear to be dry, then I'll stick my finger an inch or so into the dirt. If the pot feels light, soil looks dry, and to the touch is dry only then will I water. Your pots are so big you could probably use 2 gallons, I use a gallon and a half for 5gallon pots. Try to use RO ( reverse osmosis) water mine is zero ppms. Do you have a ppm and pH meter? If you know exactly what's going into your soil, it makes it easier to dissect what the issue may be. When I water I take ppm and pH readings from my 20% run off to insure my plants are not getting more nutrients than they can use. Also allowing the 20%, run off aids in removing all the old build up and stagnant sludge. I'd suggest looking into fox farm line of soils. I use happy frog for seedlings as it doesn't have alot of extra fertilizer being as seeds get all they need from their casings. Then after about 4 or 5 nodes I'll transplant into fox farms Ocean Forest it is pack with organic food. I usually don't start using nutes until late veg or I'll push over 3000ppms even using a quarter of the suggested serving. Fox farm also has peat moss and perlit already added.
If you had a deficiency your leafs tips would be curling up or down is a constant sign of lacking or too much being as your leaves that aren't dying are dropping but look relatively healthy I would suggest over watering.