Nute burn, Mn or Mg deficiency?

Hello!

I'll start with "the bigger picture":


(in the picture above, I have circled an example of my problem)

Close-ups:





Okay, so my 7 girls have been in veg for 4 weeks and in flower for 5 weeks - so far with no problems, until yesterday. The grow is indoor in good quality soil, 7 plants of Arjan's Haze #3 under a 400W HPS with 2 fans for circulation and an AC for temperate regulation. For nutrients I am using BioBizz Grow/Bloom/Topmax and a little bit of epsom salt. Last grow I experienced a lot of nute burns, so this time I didn't give nutrients until the 5th week and that seemed to work fine. My water is pH 8,2 so I add 6-8 drops of Nitric acid with every 1,5l water to get the pH down to around 6. Every plant gets one 1,5l bottle of pH-corrected water + nutrients at every feeding. I am following the regular BioBizz grow schedule for All-mix with very small additions of epsom salt to get the Mg necessary:
http://www.growing-life.com/shop/biobizz_grow_chart.jpg

Now to my problems.

3-4 days ago i was worried i was giving to much N and to little P/K because I felt I was seeing to much foilage and too little buds. So, I gave one feeding with NO Grow, NO Topmax and pretty much Bloom, around 3ml/l (I have never given more than 2 ml/l Bloom before) - and I suspect that this feeding caused my problems. I don't know if too much Bloom caused nutrient toxicity, nutrient lockout or if my problems are totally unrelated (which I consider unlikely).

I've read many different guides to nutrient deficiency/toxicity and among the problems described, Manganese deficiency seems to be the one that fits best:

Manganese Deficiency: Interveinal chlorosis of younger leaves, necrotic lesions and leaf shredding are typical symptom of this deficiency. High levels can cause uneven distribution of chlorophyll resulting in blotchy appearance. Restricted growth and failure to mature normally can also result.

Click to expand...

Blotchy seems a good description, doesnt it? It seems like the mid-level leaves are affected first, and the oldest and biggest leaves are affected the most. The symptoms described in relation to Magnesium deficiency also seem quite relevant.

But since this happened right after I overdid the BioBizz Bloom, one would immediately suspect nute burn, right? The problem is, nute burn is supposed to show at the tips of the leaves at first, and this seems to go straight to the main leaf surface. It is not focused to one plant, at least 4 of the 7 plants is showing symptoms and they all began showing at the same time - evidence that points to my screwed up last feeding being the culprit.

So what do you guys think? Nute burn? Some kind of deficiency? pH problems?

And please do not recommend me to flush. That is a last resort for when you've really screwed up the soil, and I haven't done anything remotely deserving a flush. Right now I'm just feeding with plain pH-corrected water, waiting for your input.

Thanks in advance!
And sorry for any spelling mistakes - I am not a native english speaker.

Peace out!

It's not nute burn. It's definitely some kind of deficiency. Most likely you've created nute lock with bad pH levels. Flush the pot thoroughly with distilled water and hope for the best.

Thanks for the quick reply, but the pH should be fine. I've pH-tested the water and in grow i had it around 5,5 then now its a bit over 6.

You shouldn't really concern yourself so much with the pH of water going in but the ph of water coming out. Flood the pot with distilled water and measure the pH of the last 10% of run off or so. That should give you a good idea of whats going on inside the dirt.

Check the PH of the run-off you get when watering.
You could also try a Cal/Mag foliar spray.
Humic acid will also help lock-out problems.
And a flush may not hurt. It's not that big of a deal to do a flush.

A flush won't help me because it doesn't tell me what the problem is, so I can't prevent it in the future, and can do nothing else than continue doing what I've already been doing, which leads to an eternal circle of fail -> flush -> fail -> flush -> fail -> flush etc.

Any idea about what the problem might be?

I still think pH problems is very unlikely, since ALL plants showed symtomps only after last feeding, NO symptoms whatsoever the 5 weeks before, and I've been using the exact same pH on the water since the start. Why would it suddenly, and aggressively, show now? It doesn't make sense.

baaamalaaam said:

Check the PH of the run-off you get when watering.
You could also try a Cal/Mag foliar spray.
Humic acid will also help lock-out problems.
And a flush may not hurt. It's not that big of a deal to do a flush.

Click to expand...

All good advice. Just make sure when you check the run off you're not using pH adjust water. You want something as close to a neutral baseline as possible. Soil has a tenancy to vastly buffer he pH levels so your adjustment one way might actually be shifting the soil pH rather than balancing out.

Xschtar said:

A flush won't help me because it doesn't tell me what the problem is, so I can't prevent it in the future, and can do nothing else than continue doing what I've already been doing, which leads to an eternal circle of fail -> flush -> fail -> flush -> fail -> flush etc.

Any idea about what the problem might be?

I still think pH problems is very unlikely, since ALL plants showed symtomps only after last feeding, NO symptoms whatsoever the 5 weeks before, and I've been using the exact same pH on the water since the start. Why would it suddenly, and aggressively, show now? It doesn't make sense.

Click to expand...

A flush can't hurt you either though. It's one of those things that's either going to be useless or help. You need to check the soil pH level anyway so a distilled flush is pretty much a no brainer.

By the way just so you know, the damage that's been done is irreversible, so don't expect it get better. If it ceases to get worse you've solved the problem.

I did like you asked and the water that came out was at pH 6,2. What do you make of that?

By the way, I am now 100% sure it is a pH problem. I did some experiments with tap water and pH down and got very surprising and disturbing results

Maybe someone can help me in the thread where I describe these experiments?

https://www.rollitup.org/newbie-central/340024-getting-very-different-results-testing.html

just buy a liquid ph kit to compare with your crappy pen lol

I cut off all the "infected leaves". Was this the right thing to do?

I did it mostly because I found those leaves disturbing and so I could more easily see any "new" infection.

Well, now im 100% sure my problem was Mg deficiency resulting from too HIGH pH, and not too LOW pH, which I thought earlier (which made me lower the pH which made things even worse).

So now I'm just gonna water with plain pH 8,2 tap water for a while too try to raise the pH.

Good to hear you figured it out. Good luck