Yellow leaves, brown spots....Help! :-)

[MassMom]

-Problem:yellow leaves w/brown spots
-Medium/grow method:Airpot with HF
-Feed and supplements used:GH Flora, micro/grow/bloom at half strength of bottle. Have followed their chart to the letter. PH 6.8-7.0
-Water source: Tap
-Strain and age: DP Think Different Auto….week 9
-Climate: 75 degrees, humidity 40
- Light used: (1) BigSmo COB (55W) & (1) GalaxyHydro 300 LED 20x4
-Additional info:Noticed yellowing last week, now see the brown spots.
-Pictures: attached below

 

[komplex180]

Ugh I hate to say this because it seems to be the answer I mostly give but, I’d guess CalMag def.

Yellowing and brown spots are normally CalMag. It maybe nitrogen, but then it would be accompanied with large amounts of lower leaves falling off daily near the bottom. However, if is an N def. you should def address that since it tends to work it’s way up from the bottom quite fast.

Hope this helps.

But if you want a second opinion from one of the best? Here you go: @Waira one of the best at diagnosis here on afn


Sent from my iPhone using Tapatalk

 

[MedGrower]

That is actually phosphorus deficiency we can observe there, perhaps some magnesium deficiency along with it too. Nothing to be too worried about it though, we see this happen from time to time at the end of the generative cycle with intense lights and boy those COB's can blast some photons. Not sure if you have enough P there but I think it is very likely you do. pH seems bit high even for soil but it still should be alright for P uptake. How close do you have the lights from the plant?

I really cannot help with how to come about fixing this though because I am just a DWC guy and don't really know about all things soil, build up of Fe and zinc can make it hard for proper P uptake but then again, better wait for more educated answer from likes of @Waira .

 

[Waira]

geez, I'm gittin' tag-teamed here!

- Hi 'Mom.... I'm with Med here on the P defc. diagnosis,... makes sense as it's highest demand right now, and you're feeding light, with no bloom boosters (high PK stuff),... I'd up the Bloom part, or maybe consider a mild PK booster, best with something that no N, as you have plenty on that from the Micro part... check out Kool Bloom liquid 0-10-10 from GH,... I think it's wise to up the Micro as well, since that has most of your micronutrients in it,...those defc.'s often show up about now as well!
... the pH, is that for the feed solution after adjusting? .. and from a meter? it is high, should be about 6.5,... In soil especially, in-pot pH can drift about quite a bit even with adjusted inputs, just too many other influencing factors in there,... I recommend getting the Accurate 8 soil pH probe (Control Wizard) for direct in-pot measurement, nothing beats that! And determining that in-pot pH is often critical to know what corrective steps to take next. If you have off-pH in there, adding more nutes will make matters worse, not better very likely! Otherwise, it's a basic lack-of defc. happening, easy to fix- .... Now, I can't tell for sure in that one pic, but I don't think I see multiple defc.'s starting, which would indicate probable off pH; another close whole plant pic or two would help, please ....Since you probably don't have an A8, we'll have to get at least a crude estimate from run-off,... this method is dubious in general, but there's an improved version run-off test and calculation in the highlighted section above this one,... a PITA too do, frankly! Orrr, do a very crude quick test of water-only (take pH of it first!) generated runoff, collected in a clean container; if it's in the 5's or 7's, we know at least that the pH is pretty badly off enough to warrant more drastic measures, like flushing... If it's OK-ish, we can tinker with nutes and pH to compensate,...

 

[Aosimple]

I have the same issue. It began when they switch to flowering. I have them on super soil so at first I just added water. I then began very light nites when it began to show P defs. My ph in has been 6.3-6.5 out 6.9-7.1 ppm 300-500 my tap water is at 300 ish, the runoff was 1500-2000 then again is super soil. I have been adding 4cc of micro and 4 cc of bloom the last two feedings. They droop but then they get up but last time I added, humic acid and a 2cc of seaweed and the in addition and theY hot really droopy, tips got yellow(some) and kind of claw look. It got better over night but the spots continue to progress. I need to water them or feed them. They are in week 6 going to 7. I have them in a 2x2 tent, under 1 marshhydro 150w and two 60w bulbs led @Waira