Need Help with this Def please guys...

Ive been having trouble with this deficency on my last couple of grows. Never had any problems like this during my 5 years of growing.

Grow room info:
Strain - Twilight
Lighting - (veg) x1 125w blue CFL / (flower) x2 200w red CFL
Temps - Max 26c / Min 15c
Medium - CANNA professional Soil (not pro plus)
Nutes - BioBizz grow / bloom
Feeding method - Hand watering
Ph Levels - straight tap around 7.0 run off comes out around 6.1-6.2 / With nutes 6.5 run off comming out again around 6.0-6.2 (using test kit as I have no pen)


P1 P2

Problem seems to start around week 3 of veg. Plant growth slows to near stop, new growth is very week with yellow veins and over time any lush older growth also dies off. Only started using grow nutes after problem persists (BioGrow 1ml per ltr) as my medium is already loaded, but to no effect.

Any help would be great guys as I want to nail this problem before I invest in new genetics. Was wondering if adding CANNA trace mix would help but Im not sure how it would react with the BioBizz.

Cheers boys and girls

Get yourself some cal-mag!!!

...and a decent ph meter and feed at 6.2-6.5.

Thanks for the quick reply guys.

As far as the cal-mag point goes. I have tried epsom salts at 1 tea spoon per 2ltr with no joy (unless its the cal im missing)

And on the Ph point. with nutes added my feed reads 6.5. when feeding straight water it is high (7.0 or slightly higher) but the medium is said to buffer ph, and with run off reading 6.0-6.2 I thought it was doing the job.

bump

I don't think those test strips are accurate, looks like almost total lockout from ph being too high.

P def. is my guess.

I'm so glad I've found someone with the same problem, been fightin this for 5 grows now 4 of which I threw the tail in and 1 it just didn't affect (idk wtf I did any different).

same mo. start about week 3-4 of veg, growth slows etc. But I'm growing lp aero not soil, I posted this up on thc talk, but didn't get any help yet:

Hi all, can ya's all help me and let me know if I'm right in thinking this is a K def (potassium)? I've taken a few of the affected leaves off and taken some snaps.

Current setup is LP Aero 50 gal res

Canna A and B nutes, benny tea.

Res temps are 68 to 74, room temp 72, ro 70%

Plants are 5 weeks into veg about 8 inch tall but very bushy having been topped a few times for scrog, was just about to put them in flower.

ph 5.6-5.9 ppm's 300-400 (I've tried running stronger, but backed off a week ago to solve this problem)
Base water is tap ph 7.2-7.4 ec0.44 or 200ppm ish (I've tried RO water but had the same problem in a grow before, I did have 1 successful grow with the tap water, idk what I did different)

Anyway folks after 4 fails out of 5 attempts, I decided it was time to eat humble pie and admit I know nothing lol, when right on week 4 the problem shows it's head in my latest attempts, having switched from dwc to lp aero in last ditched effort to solve the problem that has plagued so many grows.


ye there's a link to the pics http://www.thctalk.com/cannabis-forum/showthread.php?77996-poss-K-def-in-veg-canna-nutes-lp-aero



I'm 90% certain it's a Potassium (K) def. I've just started foilar spraying with a weak 1/2ml/ltr ionic boost high P and K, to see if it helps. I don't think mine is from a ph issue, I'm anal about PH, lol use 2 meters (calibrated weekly) (same for my ppm truncheon and ec meter) I then even take the average of the 2 readings, my ph is pretty much always stable.

Eagle, am I right in thinking that the yellowing in the centre of the leafs happens last and the first sign of problems are the leaf tips start to die off followed by the leaf edges?