HELP! Yellow / brown spots on leaves

[Weebay]

Hello everyone.

It's my first ever grow here, and I'm growing in a really tight space. (low ceiling, not even a meter high.)
Everything was peachy up until week 5 and flowering began.
On Saturday I saw some yellow / brown spots on my big leaves that were close to the LED light.
I only saw it on two leaves on the tippy top of the plant.

Today i'm beginning to see more of those spots and i'm getting scared.
I already made everything i could to make space between my plant and the LED, but i'm wondering if it's really light stress or maybe something like Calcium deficiency, nutrient burn?

i'm using Plagron Natural bloom as my only source of nutrients and using 8Ml for 2.5 liters every other day. My light is a 300W led
Strain: Royal dwarf Autoflowering

Could someone offer some advices?

Thanks a lot

Edit: i added a full picture of the plant, i suppose there are a LOT of mistakes on this shot, so please fell free to give guidance l

[Canuck147]

Properly pHing your water? What kind of grow medium?

[Weebay]

Yeah, I have a PH meter, telling me 7.0, but i'm not the most confident in the efficacity of it =\
I'm growing in coco soil.

[TOKABIGONE]

Welcome Weebay In coco it is critical to be sure of your pH going in is kept between 5.5 to 6.0. The low end pH meters are notoriously inaccurate. Use strips or drops to be sure. Review the GWE tutorials on pH management and adjustment. Good growing!

[Weebay]

Thanks a lot, i just ordered strips.

So if I understand, the spots really look like its a ph problem?

[TOKABIGONE]

Yes I would say it is. I had similar leaf markings early on in my grow and quickly resolved the issue by getting under 6.0 pH. Coco is a lot diff than soil grows because it is inert but changes quickly in pH when nutrients are added so be sure to check after you add them to your water. Also is that blurple light 300 watt true draw from the wall or what the manufacturer claims as output?

[gbauto]

Looks like a Ca deficiency, those spots are signs of the plant attempting to translocate nutes from older, mature leaves to new growth.
Ph is a critical parameter you need to control so that all of the nutrients are available for the plant to uptake.
Two key items you really need to track in any grow are the ph and ec/ppm of your feed stock.

[Weebay]

Thanks a lot for your answers guys.

I was also thinking about CA deficiency. I can't get any before tomorrow, but I'm going to try calcium supplementation as soon as I can

@TOKABIGONE Here is the link to my actual light : https://www.amazon.fr/gp/product/B07...?ie=UTF8&psc=1

just read the PH article lkike you recommended, i will get some PH up and Down too tomorrow

I'm going to add some pics on this post, if you see something alarming, please fell free to tell me

[TOKABIGONE]

Hey, so I checked the specs on your lights and found it is 130 watts true draw which is not enough for a productive flower. 300 watts true draw is what you want, not the false claim the manufacturers advertise. You'll get some but not near what is possible with proper lighting. I'm sure you already know that you need a taller tent but we work with what we got and budget allows. This is a fun and rewarding hobby and certainly not without challenges. Happy Growing!

[Weebay]

Wow, thanks a lot for the research. I will be upgrading the day I can change the tent.
I would have never thought lighting could be a problem with such a tiny tent.

I finally found a place open today and had wonderful hints.
He told me that plagron natural wasn't the best for coco, and It's why I clearly have CA deficiency.
I bought fertilizer made for coco, so I should get better results now since there is CA and manganese in it.
i Also got a drop ph tester, ph up and ph down. i'm fully equiped now =)

Thanks again for the guidance, I'll upgrade once i get to harvesting!

One last thing though, in your opinion, would it be worth it in the meantime, to add a 80 watt lamp like this one?

https://www.amazon.com/Spectrum-EWEIMA-Dimmable-Lighting-Control/dp/B0899SPHYJ

[gbauto]

A simple rule of thumb when running current-technology white diode boards or strips is 120-watts will cover a 2x2 footprint in flower(which is about the size of the plants I grow).
Since QB style panels are pretty common and they typically run at approx. 125 watts, using a panel over each plant will crush it.

[Spog]

Hey not 100 but I think I see clawing check out the plant problems on the site for clawing or see if any one else does

[Weebay]

A simple rule of thumb when running current-technology white diode boards or strips is 120-watts will cover a 2x2 footprint in flower(which is about the size of the plants I grow).
Since QB style panels are pretty common and they typically run at approx. 125 watts, using a panel over each plant will crush it.

If I follow you rule, my 130 Watt is enough for my setup?

Hey not 100 but I think I see clawing check out the plant problems on the site for clawing or see if any one else does

I'm pretty sure you are right, I had clawing, just checked on it, it's gone. I think it disappeared when I got the light further away from the plant a week ago

[gbauto]

If I follow you rule, my 130 Watt is enough for my setup?

Using power(watts) as a metric isn't universal.

Because there is a HUGE difference in the efficiency of white diodes vs. 'blurple' monochromatic diodes(as in over twice the light output for each watt of power used), that's why I used the qualifier 'current-tech diodes' in my original post.
I suspect that's an older style 'blurple' fixture you're using-because those diodes are not very efficient I would double the power density to achieve adequate light levels.

[Weebay]

Thanks a lot, i'm going to buy a second light.

[Weebay]

Hey everyone,

I'm back =)

it's been a week or two and i adjusted my nutrient, made everything I could to put some space between my plant and the LED panel by low stress training.
I added the lamp I linked to put some lights on the bottom buds, I trimmed a lot of big leaves to allow more air / light distribution.

Sadly, I'm getting a lot of clawing and "burn marks" on one of my main branch

I suppose it's light burn, and I will not be able to do anything about it, but, could it be nutrient burn? Or anything else? I'm adding photos taken a minute ago

I should be good on CA now, i have the right fertilizers.

[Balu]

I wouldn't say it's burnt, how much EC do you have? Rather excess calcium. Burned curls down, lack of cal-mag curls up.