Nitrogen Deficiency or a Magnesium Deficiency or something else?

[leopard]

Strain - White Widow
# of Plants - 1
Grow Type - Hydro
Grow Stage - Veg
Setup - DWC
Light - 600 Watt HPS
Nutrients - General Hydronponics
Medium - Grodan Rockwool
PPM - 900
PH - 5.8
RH - 50% to 55%
Room Temperature -78 to 84
Solution Temperature -65 to 69
Room Square Footage - 20
Pests - None Known

Problem:
as pics show below

Is this a Nitrogen Deficiency or a Magnesium Deficiency or something else?

 

[J189RFC]

What really funny about deficiency is that they all look somewhat similar. It is fairly difficult to burn your plant in my experience. I've had more deficiencies than burns and thats cause, as we all know, she is a HOG for nutes!!

So to me it does look like N def, but add a general boost of 20-20-20 (or basic grow) + a little N and I think she will pick right back up!

 

[J189RFC]

 

[JJ Bones]

I agree, I would say nitrogen. Try a foliar spray to help out.

 

[paddywest]

I'm wondering if my Critical Mass plants below are suffering from a Magnesium deficiency? Or is there some other deficiency at play? I'm in Hydro, using Plagron, keeping pH between 5.5 and 6 (mostly), using Reverese Osmosis water because my supply is extremely hard. ( I use 2/3 RO and 1/3 tap) I've found that my yield is not what it has been with other plants in the past namely Mazar, which was a treat to grow. These ones pictured below are the fifth generation by cuttings. The last crop only gave about 1.25 oz per plant. All items such as light, air replacement, etc are spot on. This is baffeling me. Perhaps it's all down to the RO which I only introduced two grows back. Note the red stems. I'd really appreciate some help. One more item, they seem to have interveinal yellowing more on the leaves that are directly facing into the lights. It has stated on the older leaves and progresed up the plant. I've been foiler feeding with Epson salts every day onw for about 10 days and change!!