[gattorama]

hi there!

I need some help with the Pure.
first an overview of my growing method: till recently I used to grow in soil, then I switched to DWC with a system very similar to this one:
https://www.icmag.com/ic/showthread.p...467#post336467

I grow in a small cupboard under a 150 watt HPS. I use a reverse osmotic filter, and General Hydroponics Europe (GHE) for nuts. (the Tripack is called, as far as I remember). Now I've also started using some general fertilizer made by Hanna (20-5-10-2mg + micro for veg. and 8-12-24-3mg for flowering).
I started growing Nirvana's Snow White, some kind of f2 derived from White Widow. I was able to get a very nice phenotype. I grew it in soil and DWC without any problems and with good results.

Recently I decided to start working with some serious genetics and choose TFD The Pure. I've got two phenos: #3 is a very fast plant, not a great producer but with a wonderful smell and taste; #1 is slower but the greatest producer I ever found. The smell is not so intense but the taste is quite good. This is my selected mum, I'd say.

Now my problems start. I've grown both phenos either in soil and DWC. Their behaviour is different but both seem to suffer for some kind of deficiency I'm not able to understand. Pheno #3 is not badly affected by the problem, but #1 is.
The problem shows up as small spots of lighter green on older leaves. This spots turn yellow and then the necrosis starts showing up.
The begining can be see in this picture:



then the problem gets worse here:




Here we are at the end of the story:



My first thought was a calcium deficiency due to the use of a RO filter. So I added some calcium nitrate to the water. #3 seemed to react well, but #1 did not.
So I thought it could be some kind of ph related problem. I tried different solution: I tried lowering the ph to 5.8 (usually it stibilize around 6.2/3). No results. So I lowered it to 5 and even lower (till 4.8) without result.

Take into account that I had the very same problem in soil and DWC, even though in DWC plants are soffering more. And #1 is far more affected then #3, both in spoil and in DWC.

I don't know what to do. Keep also in mind that I'm growing, in the very same environment, my Snow White pheno without problems.

BTW, I'm getting some nice buds:

but I'm sure I could get some better stuff.
Can you help please?
thanks for your kind attention.

[Crowmax]

Looks like a Magnesium deficiency

[gattorama]

Originally Posted by Crowmax

Looks like a Magnesium deficiency

Thank you Crowmax for your kind attention.
Well, actually a Magnesium deficiency was my first thought. Still, my nuts have a 2% of Magnesium: it could be not enough.... So I add half a teaspoon of epson salt every 4 liters of water, with no result.
Moreover I've read that a Magnesium deficiency shows up as necrosis starting from the border of the leaves, whereas my problem shows up in the middle of the leaves...

It could be something root related.... I don't know.

Thanks.

[Crowmax]

Hmm, too bad that didn't work :/

If you using city water, maybe is a poor quality?

hi gattorama

i think your problems are coming from the switch to hanna nutes. i've no exp of hanna nutes but know that changing feed regime in middle of grow can cause lock-out, pH troubles, and a confused and stressed plant. i suggest you go back to gh triple pack if possible.

i think you and crowmax are correct in your diagnoses as either calcium or magnesium def. it sounds like you know what you are doing.

if i was you i would flush the plants thoroughly, change the res water in the dwc. then start feeding gently with gh 3-part, adding a little superthrive and a bio stimulant such as cannazym or bactivator. [edit - if in flowering don't add superthrive]

my experience with the pure is that it sucks up the nutes and once established in veg likes an ec of 1.8-2.

those leaves look pretty dry. and looking at the pics again i think perhaps radiant heat damage? what are your temps and humidity?

the snow white, being a widow descendant, will require less nutes than the skunk, which is hungrier. this may explain why the sw is ok.

your pH for soil should be up near 7 while for dwc 5-6 is about right.

the widow is notoriously picky to grow while the pure is notoriously robust so it is baffling! but hope some help.

edit: you'll probably get more help posting this question in the sick plants/infirmary forum.