Sulfur deficiency? Maybe N?

[fear.loathingSF]

How long has this problem been going on? This problem has been progressing for about a week, maybe less.
What STRAIN are you growing? Purple Kush
What was the establishing technique? (seed or clone?) Clone
What is the age of your plants? 12/12 for 26 days
How long have they been in the soil mixture they are in now? Since ~4/20 when they were planted
How Tall are the plants? 2-2.5 ft.
What PHASE (seedling, vegetative or flower) are the plants in? flower
What Technique are you using? (SOG, SCROG etc) none
What size pots are you using? (Include how many subjects to pot) 1 Plant per 3 gallon pot
What substrate/medium are you using? What brand of soil mixture are you using?(percentage of perlite, vermiculite...etc?) FF Ocean Forest amended with dolomite and perlite
What Nutrient's are you using? FF grow big, FF big bloom, FF Tiger Bloom, Grandma's Molasses
How much of each nutrient are you using with how much water? *Knowing the brand is very helpful* in a 5 galllon reservoir that I water from I usually use 3-4 TBSP Big Bloom, ~7 tsp tiger bloom, 3 TBsp Molasses, and just last watering I added 3 tsp grow big
How often are you feeding? I have been feeding for most waterings, sometimes I will skip a feeding
If flowering, when did you switch over to using Bloom nutrients? started boom nutrients right when I switched lighting
What order are you mixing your nutrients? (example: veg nutes 1st, bloom 2nd ect) This matters? I don't have a set order
What is the TDS/EC/PPM of your nutrients used? dont have EC pen yet
What is the pH of the "RUN-OFF"? ~6.5-7 with aquarium test kit
What method of pH test was administered? Using Strips? pH pen?
How often are you watering? every 3-4 days or as needed. I check overall weight by lifting and moisture w/ a crappy meter
When was your last feeding and how often are you feeding? last feeding was yesterday, I feed during most waterings.
What size bulb are you using? 600 W HPS
What is the distance to the canopy? ~2ft.
What is your RH Factor? (Relative Humidity) 45-50 day, 50-70 night (working on lowering that)
What is the canopy temperature? 78-80 day, 65-70 night
What is the Day/Night Temp? (Include fluctuation range) 65-80
What is the current Air Flow? (cfm etc.) 200 cfm exhaust,
Tell us about your ventilation, intake exhaust and when its running and not running ? 200 cfm exhaust and 6" circ fan 24/7
Is the fan blowing directly at plants? all plants get a gentle breeze, nothing extreme
Is the grow substrate constantly wet or moist? I let the top dry between waterings, its usually somewhat moist
Is your water HARD or SOFT? soft
What water are you using? Reverse Osmosis (RO)? Tap? Bottled? Well water? Distilled? Mineral Water? tap
Are you using water from a water softener? no
Has plant been recently pruned, cloned or pinched? just secured w/ bamboo and some branches tied down for more light, no cutting
Have any pest chemicals been used? If so what and when? nope
Are plant's infected with pest's? nope

Some of the fan leaves on my purple kush clones have been yellowing out the past few days. The problem seems to be more near the top of the plant and only fan leaves are effected. The smaller leaves next to the buds look a more normal, darker green. I fed some grow big last feeding(yesterday) in case it is a N deficiency but it did not seem to help. The feeding was medium, not too weak or strong so they may have not gotten enough N, I don't know. I think it is too early for the leaves to start yellowing, right? this is day 26 of flowering and buds are scheduled to ripen at 56-70 days.

What do you guys think I should do? Many thanks in advance

 

[LlamaSchool]

I'm not an expert on this stuff but I do use a very similar nutrient package. My first impression from your pictures was a pH issue or nutrient toxicity. I believe curling/necrotic leaf tips are a symptom of this.

1. I see you test the pH of your runoff but what is the pH of the nutrient mix you are giving them? Tiger Bloom is very acidic but your probably know that.

2. You are definitely feeding your plants at the upper end of the acceptable limit for Tiger Bloom. I believe the feeding chart suggests 1-2 tsp (5-10ml)/gallon of Tiger Bloom and I don't think you need more than 1 tsp(5ml)/gallon for most varieties. If you have 35ml TB plus 60ml BB (prob not an issue) plus GB (even though 15ml isn't much) I think you have more than enough nutrients.

3. Finally, even though the Fox Farms bottle suggests that you _can_ feed with every watering, their website suggests feeding with every other watering. I think this might be a good idea to help flush out accumulations of salts but again I have no real scientific basis...just following instructions...

 

[kushism]

follow this quick and easy questionnaire, it has pics to make it easier.. there is a good chance you will figure out this deficiency, and all future ones

http://www.icmag.com/modules/Tutorials/PlantTrouble/Merged.htm

i think this is the end-all when it comes to figuring out deficiencies..

hope it is helpful

 

[fear.loathingSF]

Its hard to say for sure without an EC pen, but from my limited experience I have an intuitive feeling that I am pushing feeding to the upper limits. I feel like there *might* be a salt buildup causing some sort of nutrient lockout. I wish I had some more toys, but I cant fit those pH and Ec pens into my budget until next month...

Now that I check my feeding mix, it is very acidic. On my aquarium test kit I get a result of less than 6 and can't measure lower than that. I do have dolomite in the soil which should be helping to bring the pH up to a neutral 7.0

Thanks for your input llama

 

[fear.loathingSF]

Thanks kushim for that link. Ill definitely keep it around but in this case I can't diagnose the problem. I have looked at so many different pictures and descriptions and am unsure that the problem is

 

[LlamaSchool]

Well I don't even have an EC reader right now either but I would at least use pH test drops to measure my nutrient mix before feeding. For $12 you can measure from 3 or 4 up to 9 or so.

Water a few times with no nutrients or just Big Bloom. Make sure the pH is right (upper 5's to upper 6'S). Use less nutrients (like 1/2 of the TB, you should be OK with the BB) or feed every other watering. If you're not using an alkaline solution to bring the pH of your mix up after adding TB you need to get something.

Also, if you are foliar feeding with an acidic nutrient mix, the dolomite lime in the soil will not help.

 

[fear.loathingSF]

I am not foliar feeding at all. I think I will give the feeding a rest for a few days, maybe just a little BB. Ill look around for something to raise the pH of my feeding mix too. If there was a pH problem in my soil I think it would be easier to detect. My really crappy probe pH/moisture/light meter is reading a pH of 7-7.1 and pH test drops of runoff indicate 6.5-7.0. I do think you are on to something suggesting that the very low pH of my feeding mix is causing problems though...

 

[fear.loathingSF]

Im noticing some brown hints between the veins of some yellow leaves now. This hobby is incredibly stressful, I hope these plants survive until harvest

 

[hazy]

iron and maybe mag

 

[fear.loathingSF]

I was sort of thinking Iron might be part of the problem from that diagnosis tool posted earlier. Yellow/white leaves with green veins is what the diagnosis thing describes. The yellow leaf fits, but my veins are purple, maybe becuase its purple kush though. So many problems seem to have similar symptoms, guess you just need a lot of hands on experience to figure everything out...

I flushed the most affected plant to see if there might be a salt buildup. If that plant improves I guess I will go ahead and flush the rest. TB has mag and Fe so I have a feeling any deficiency is the result of a lockout/pH problem rather than a true deficiency