Plants need professional help....

[Raistlin1968]

Big hello to everyone who stops by...

So I'm seeking help because a pair of my plants are having problems...
Firstly I'll start with my setup.I have a 1m by 1m by 2m grow tent and have a ATS300W Pro Led Lumatek...
These are my 6 week old autos...



As seen in the next photo I'm having problems with number 1 and 2...



1 has white tips on the leaves and 2 has yellowing leaves...now I have been looking online and I'm torn between light burn of nute burn.
Here's the thing...I give all the plants the same amount of water,feed and care.I even try to keep them all at the same height adding or removing blocks of wood depending how tall some grow compared
to their siblings.I keep my light source 50cm above the canopy starting with the lowest setting and have been incrementing the power to the highest setting over the last 4 weeks.Also I have only given them half the stated amount of feed twice in the last 3 weeks. Plants 3.4 and 5 are doing well no white tips no discolored leaves.
What am I doing wrong? Any and all advice welcome...and thanks in advance to everyone.
P.S...Here are a close up of some leaves from both plants...

[dirtymike]

Light bleaching is my guess. What is the DLI you are using? Auto's so it's would be for 18 hours. Correct??

[Raistlin1968]

The DLI is around 35 and I've had them on a 20/4 light schedule.Which I have just changed to a 18/6 schedule.Does that sound about right..?

[dirtymike]

35, that should be ok. If any protons don't get absorbed they create heat. Cannabis can take 40-50 DLI as long as the heat is disapated and correct nutrients are available. Moving lots of air around could help. That deep into flower and you should see some movement with air. Tag the worst leaves and go to 18/6. Auto's will do well there. Might raise the light a inch or two, maybe. I tend to do one thing at a time and wait a day or two to see what happens but I'm lazy.

[Bluey]

You may have an early stage potassium deficiency. Now is the time PK deficiencies start to show if you don't start supplementing your base flower nutes.

What medium are you growing in and are you measuring the pH of the feed water?

First lot of pics plant on the right looks to be praying hard with nute burn also but hard to tell. Lifting the light a bit is a good idea.

[Raistlin1968]

Hi Bluey,so I have raised my lights and bought some soluble potassium, should I add it in every other watering like the feed or in every watering till I see they're getting better? Also thanks for the advice...

[Dgrobro]

I’m with dirtymike. I bet it’s a DLI/PPFD issue with the light. Whatever the issue for me it’s way better to eliminate a potential issue. Then I can move on to solving the problem.

[Allenpro]

I think its nute burn and your N is blocking the P&K, is this a soil grow? Could also be the feed PH is off. 35 DLI shouldnt burn anything
BTW, what strain is that and who is the breeder? You cant ask for better stacking buds then I see on #1 & 3. and I cant tell you how it pains me to complement a autoflower

[Raistlin1968]

Hi Alienpro, so yes it is a soil grow, and they are 1-4 Sweet Gelato Autos from Sweet Seeds and 5 is a White Widow Auto gifted by Sweet Seeds so I guess It's generic. I try to keep my Ph between 5.5 and 6.5, I've raised my lights only they cant go any higher now, should I lower the intensity to 75% do you think..? I've had overfeeding problems in my last grow so now almost in their 7th week I've only fed them 3 times with half the recommended dose. I've bought some potassium for the ones that have yellowing leaves as Bluey pointed out. Also it's the first time I've used my new ATS300W Pro Led Lumatek, so I guess I'm still trying to figure out the height and intensity needed for each phase of growth. If you have any advice on that topic It would be priceless.Thanks for compliment and any kind of advice will be awesome.
Thank you.

[Allenpro]

I got your message, I did some research pn that light and it does put out enough PPFD to burn your plants., I will post the PPFD map at the end of this thread.. Did you get a phone app to check the PPFD and DIL?

[Bowhunterwoody]

In my experience the light tips are a sign of light burn. Darker brown tips can be sign of nute burn. Praying and bleached edges are a pretty good indicator of light stress. All the plants in the pics look like they have light stress to some extent. I'd definitely back off the light some.

[Allenpro]

Either way would a good flush hurt anything? I dont grow in soil very often so I dont knon

[Smallgrow]

I struggle with light burn I also run a lumatek (Photontek in North America) light. Not that one but I bet the diodes are the same. Just a thought

[Allenpro]

This is the posted PPF map for that light and unless they exegerated yes you could have some light burn but I still thing its nute burn so I would flush and go back and feed at 1/2 strength

[Raistlin1968]

Thank you so much Alienpro will be trying out these heights ASAP. I have the Photone App for Android, hope it's good enough.

[Smallgrow]

Make sure you check your phone model against Photone s list to see if you need to calibrate it. I have an IPhone so you’ll have to see what they say on their app or website

Also remember it’s a balance between nutes and light. More light needs more nutes as you push the plant. If you have less light you plant will need less nutes as your not pushing as hard. This can result in excess or deficiency even when it seems like you’re doing it by the book.
Practice makes perfect, keep at it your doing well