Help! N def or nute burn? - pics

[Mad Woodsman]

this blackjack (in biobizz allmix soil) is at day 20 in flower, and I'm getting a lot of yellowing of the leaves and seem to be loosing a lot of foliage.
I don't know if it's N deficiency or nute burn.
I've been feeding it with 0.5m/l of biogrow and 1ml/l of biobloom per week (using about 600ml of water per feed), which is half the recommended biobizz amount for allmix, with a watering of de-chlorinated, ph adjusted, tap water in between (every 3 or 4 days).

I flushed it today with about 1.5 litres of water.

it's had about 3 feeds since it went into 12/12 4 weeks ago.

it's my first grow and only plant and I would hate to loose it at this stage!
I would be very grateful of any help or advice on how to proceed.

here's my ongoing journal with more pics and info:
https://www.420magazine.com/community/threads/madwoodsmans-1st-grow-blackjack-soil-cfl-closet-2011-a.152730/

some more info:
lights:
250w 2700k CFL
2 x 23w 2700k CFL

space:
2x2x4 feet closet.

temps:
63F min to 78F max

RH:
42-45%

 

[CannaVince]

Re: Help!! N def or nute burn?? (pics)

Def not a phos def....I believe this is a clear case of Nitrogen and Zinc def....should be easy to correct... Flush her out and give her a 50% dose of your nute reggies....for nitrogen that is .....

 

[CannaVince]

Re: Help!! N def or nute burn?? (pics)

Don't forget that they are a bit along and will start to do this anyways....using up the nutrients in the fan leafs.....

 

[QueenTokelove]

Re: Help!! N def or nute burn?? (pics)

No advice to give but wanted to say that they look good...

 

[Mad Woodsman]

Re: Help!! N def or nute burn?? (pics)

Def not a phos def....I believe this is a clear case of Nitrogen and Zinc def....should be easy to correct... Flush her out and give her a 50% dose of your nute reggies....for nitrogen that is .....

thanks for the replies folks!

so Vince, I should give her a 1/2 dose of my Biogrow and leave out the Biobloom in my next feed?
If it's a nitrogen def, should I be upping my Biogrow amounts at feeding or just keep going the way I've been going (1/2 strength)?

I only started feeding her nutes when I flipped to 12/12, as the Allmix was pretty nute heavy to begin with, but maybe should have started to feed her earlier.
I figured they would be going a bit yellow at this point anyway, but thought it might be a bot early for all that yellowing!
Maybe the zinc is getting locked out due to a high ph.
My tap water is pretty hard here, though I try to ph balance it with lemon juice before I feed.

 

[CannaVince]

Re: Help!! N def or nute burn?? (pics)

Oh yah lets see....um knowing you hadn't given nutes till 12/12..I would just give her a full dose of biogrow...what is it like a 6ish?... That would be kewl... Might be locked if it's ph is wack....than a small amount of cal/mag would provide the zinc.. You need to get that ph right first....

 

[FrankFoster]

Tox lockout bro. Your ph is whack and the only thing you can give her is straight Kentucky bourbon mixed with two parts soda and with a dash of lime.

You also need to make sure you haven't got tds tox.