Light stress?? Please help diagnose my plant issues!

[greenman12345676543]

Hey all, at my wits end with trying to figure out what is wrong with my ladies any help or advice would be massively appreciated

Im running Athena nutrients, two feeds a day in 3 gallon pots with 10-15% run off. Coco perlite mix 70/30

Ph is 6~ and 3 EC (as per Athena guidelines) while run off is coming out at 3.5-4.2 EC and ph is 5.7-6

LED lights are roughly a foot above the canopy

It started with the tips of the fan leaves going yellow and turning upwards and slowly progressing throughout the rest of the leaf. My environment is about spot on (I think) 25 degrees Celsius/ 77 F, with the humidity at 51~

They are at the start of week 3 and the yellowing is progressively getting worse

Cheers

[golfnrl]

Your grow conditions sound good. I'm assuming these girls are fem photos? What kind of light are you using? Are you following the manufacturers recommendations for how high above the canopy the lamp should be at this stage of growth? Have you checked out the Plant Problems button at the top of this page?

Fans are solar panels, right? The plant stores energy in them and uses them as needed. As the stored energy is used up the leaf yellows and dies. That could be what you're seeing.

What's you're plan on defoliating? The plant in #2 looks like it might need some thinning out in the middle and down low.

[dirtymike]

Checking run off you will get alot of different readings. Flower's are demanding more nutes so it takes it from the fan leaves causing nute loss in some of the leaves. You have burnt tips on some of the fans also, my guess it to much love.

[Bluey]

It's nute burn. Reduce EC and suppliment with ¼ to ½ strength PK. Increase fertigation to 3 times or 4 per day. Pots are small and will be tough to manage moving forwards. Increase pH in a range to 6.25 averaging 6.1 slowly increasing to 6.2.

Reduce light output marginally to make it easier to manage

[9fingerleafs]

Magnesium deficiency and the EC is too high. I explained in the other post

[Bluey]

Yes it is showing that. Do you correct it by raising pH above 6.2 so it will take it up or do you suppliment it even though she is in flower?

[9fingerleafs]

I would lower the EC to 1.5 and then add magnesium. Maybe epsom salt. Maybe even one big flush with the right ratio of nutrients but I don't really do that myself. Then when the leaves recover some pk boost could be added around week 5. I don't really monitor pH too close. I always aim for 6 Ang got my own environment dialed in. Maybe because the runoff is lower some increase will help balance out but I don't think it's the main issue. The EC is too high and the tips of the leaves are burning. That means toxicity of some nutrients preventing others from being absorbed. That itself could create an accumulation of nutrients in the medium lowering the ph. So low runoff ph it's a symptom not a cause in my opinion

[Bluey]

I agree. Get EC to under 2.0. 1.5 would be good and adjust from there watching new growth.

I also agree right now may be a week or two too early for PK.

I don't know which method would be best for dealing with the calmag def but I think both would work combined with the drop in EC. Your method probably quicker.