Please help identify / solve this deficiency. Iron or Sulfur or ?

[hyper-piper]

What Strain is it? Jamaican
Is it Indica, Sativa or Hybrid? What percentages? Not sure think its Hybrid.
How Many Plants? 292
Is it in Vegetative or Flowering Stage? Flowering
If in Vegetative Stage... How Long?
If in Flowering Stage... How Long? 3 weeks 6/7 days (almost 4 weeks)
Indoor or Outdoor? Indoor
Soil or Hydro? Soil
If Hydro, Reservoir size?
If Hydro, Reservoir Temperature?
If Hydro, what type of Medium?
If Hydro, what type of Setup?
If Soil... What is in your Mix? Promix hp
If Soil... What Size Pot? Large continous beds (3150 ltrs of soil) 5x5 feet per light with 1x5 foot between.
Size (Wattage) of Light? How Many? 1000w 7 lights
Is it Air Cooled? 6 ton AC cooled
Temperature of Room/Cabinet? 82-84 day / 72-74 night
RH of Room/Cabinet? 50-60%
PH of Medium or Reservoir? 6 - 6.4 for soil. 5.7 - 5.8 for runoff.
Any Pests? None yet
How Often are you Watering? Every 2 to 3 days (35-45 gallons)
Type and Strength of Fertilizers used? Gen Hydro / Aussie / Massive / Carbo. 1300 - 1500 PPM per feed. Run off at 800 ppm when tested.
Size or Square Footage of Room? 300 sq ft.

Problem: New and top leaves turning pale green (slight yellowing) from center of leafs to edges. Only the tops of the plants and upper leaves affected. Small leaves around new buds are not yet affected. The veins on the outer edge also yellowing while inner leaf veins remaining dark green. Looking around this appears to be either iron or sulfur deficiency but hoping some one can give some confirmation. Can't determine issue on the Plant Abuse Chart nothing appears to be similar to mine. I'm thinking I should continue with foliar sprays of Calmag or Epsom salts.

Or any other ideas / suggestions.

History: Had a Mg deficiency on lower leaves during week 2 - sprayed Epsom salts and Calmag which did help. Determined it was a Mg def originally as the yellowing was between the veins which remained green (inter chlorosis). The lower leaves were most affected.

Thank You.

 

[Setting Sun]

have you continued to supplement with cal-mag throughout the grow?

if not, you probably having mag deficiency again.

 

[Screwnuts33]

Has it been awhile since they had any nitrogen? Looks like your runoff water is a little low on PH. May need to sweeten your soil a little.

 

[hyper-piper]

Setting Sun: Yes I have continued to give them the Calmag after the initial Mg def. I didn't think it was Mg anymore as it is a mobile nut and should be taken from the older leaves? That's why I started to look at an Iron or Sulphur def. A few plants also getting the cupping of the upper leaves which also points to a Mg def (from what I have read). Oh so difficult to pin point a def as it seems to be a combination of many.

Screwnuts33: Your right the runoff is low and nitrogen may be playing a small role. Brand new dirt this round - hasn't had time to build up yet. I have given them 2 big feeds and one watering since the initial post. Things have started to green up.

I have also been foliar spraying them with Calmag every 3 days which appears at this point combined with the feedings to be helping a lot. I have included a nice before / after picture.

Everything looks good with the actual flowers - once you tear off the shade/fan leaves they are starting to come together.

And finally a small section of the family happy and getting green!

Keeping my fingers crossed for another 4 weeks until harvest.

Thanks for the responses!

 

[Setting Sun]

Glad they're doing better.

Beautiful canopy of buds!

 

[C5Rftw]

yah i had a bad mag. def. a while back. cal-mag cleared it right up... good stuff.. i use it everytime i flower now.

your grow is looking great man, good job