Need help diagnosing!

Hi everyone, beginner grower here and this is my first time taking my issues to the forum.
Let me fill you in with what is going on... this is probably my 4th or 5th grow and my first grow in soil (coco coir). Since I've started growing hydro has been all i know. Right now i have two MK Ultra's and two autoflower Bubba Kush's. All are 4 weeks 1 day old. Roughly two weeks ago i started noticing what i thought to be a nitrogen toxicity. I gave them a half strength feeding hoping to see improvements: no luck. Color stayed the same and soon after started they showing brown/shiny spots on the leaf edges and margins. Since then it has only worsened, i have tried ph'd flushes, half strength feedings, but am getting nowhere. Having never seen this in hydro i am truly out of ideas, the combination of symptoms has me stumped. I have feedling logs and can provide countless pics of each one of them basically since they sprouted and will happily share anything needed. I realize ive left out a lot of specifics on grow room conditions and factors so feel free to literally ask anything and i will give you as much information as possible. Seeing them like this breaks my heart, even more so now because im at a dead end, please help me save them! All of your comments are very much appreciated. Thank you!

how often are you watering? looks like an over watering issue.

whats the RH in your room? and how much air do you have moving in there? might be a low vpd problem

Watering as needed, in my 6 inch square pots it was about every 4-5 days. But last feeding they drank it all in 3 days, i noticed slight nutrient burn so i gave them ph'd water last night . RH is 60-70 right now but i recently moved them to my tent in the same room where it stays around 40. My room circulation could definitely be better, i have a small desk fan in the tent and a fixed fan for moving air in the rest of the room right now. Also an air purifier in the opposite corner but that doesn't push much air.

And not one mention of pH...............
http://catnews.org/FREE Pot Books/Marijuana Garden Saver [2005].pdf

it doesn't look like a ph problem. no reason to mention it if thats not what it is

Treefever said:

Watering as needed, in my 6 inch square pots it was about every 4-5 days. But last feeding they drank it all in 3 days, i noticed slight nutrient burn so i gave them ph'd water last night . RH is 60-70 right now but i recently moved them to my tent in the same room where it stays around 40. My room circulation could definitely be better, i have a small desk fan in the tent and a fixed fan for moving air in the rest of the room right now. Also an air purifier in the opposite corner but that doesn't push much air.

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air purifier? like a hepa filter? or like an ozone generator?

As i said. I have left out a lot of details. Ask and i will answer. Ph is 6.3 runoff is 6.2 And yes its a 3 in 1 hepa filter. Germ guardian model

Roger A. Shrubber said:

it doesn't look like a ph problem. no reason to mention it if thats not what it is

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Run with that.....

Going "Yellow" from the bottom up. I wonder......

if you're growing in coco, you need to be watering more often. you do not want coco to dry out completely, ever. also 6 inch pots may be part of the problem, your plants are probably pretty root bound. i know people say you can grow big plants in little pots with coco, but why do something you don't have to? being able to doesn't make it a good idea.
i'd repot into two gallon pots, and start watering daily, with 1/4 to 1/3 strength nutes. if it seems like they need more food, give them more, just watch for tip burn and back off a little if you see it.

Never water without fertilizer in coco. Even if you just add a reduced amount.

Ok, noted I was planning on going to at least 2 gallon smart pots next, i still need to purchase some but will asap. I will lower nutes to 1/4 strength and monitor for changes and also stop giving plain water. Ill be posting an update with pics soon! Thank you!

Hello again, hope you all had a great weekend! Would've posted sooner had i not been busy. To give you all an update: I translated all four girls into 3 gallon smart pots on the 26th. Since then ive given them 2 quarter strength feedings, the 2nd one being this morning. Unfortunately i havent seen any improvements, quite the opposite actually. The color and spots continues to make its way up the plant to newer growth, the plants are fading. And becoming covered in these awful looking spotty leaves. Temp, humidity, and ph is still looking good. At this point im almost ready to give up on them, i have had multiple suggestions from people on forums and my local grow shops, and nobody seems to be saying the same thing. I will add more recent pics for anyone interested in looking. I just hope i can avoid this in the future with soil grows! Thanks again to everyone for your suggestions.

Treefever said:

I translated all four girls into 3 gallon smart pots on the 26th.

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What language did you use?????

Have you checked the pH going in against the run off?? Your plant is LOCKED OUT.
I have a Mother Plant that looks like that.... Flushed her with 6.0.... She gave me back 5.2.
After she got a wash and a re feed she bounced right back

Jypsy Dog said:

What language did you use?????

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Oops... lol

I checked the runoff 2 feedings ago and it was only a point under what i fed it: 6.3. I probably should've checked again this morning...Someone said earlier that i should never water coco without nutes, is this an acception if i am trying to flush a lockout?

Imo,

First thing I would look is....where did the problem started...from the young leaves or the mature leaves. Your pics says it's starting from the mature leaves. To me, that means 'mobile nutrient' problem if not pests. Then I correlate this assumption with the data you provided. What stands out is your ph run-off is at 6.2-6.3. Looking at a ph chart, tells me that your plant cant absorb P (phosphorus), Ca (Calcium), and Mg (magnesium) which are only available at above ph 6.5 assuming coco coir is similar to soil.

That said, based on your pics, looks like a phosphorous + magnesium deficiency problem

It wont hurt if you raise your ph closer to 7, if that would solve the problem.

Just saying

Definitely the older leaves first. And that makes a lot of sense, my first thought when it showed was a P deficiency. I guess i overlooked the normal ph levels for soil, learning new things everyday since my switch from hydro! Ill make sure to raise the ph next feeding