Help! Can't let this get em now!

[MakeItRain69]

-Problem: Overall color fade, rusty/brown splotches that start near the base on the vein and move down the leaf, looks like older leaves and newer leaves are affected.
-Medium/grow method: Organic potting soil mixed with 20% Coco. Realized about a week ago that this soil was already fertilized, 15/13/15 with added Ca.
-Feed and supplements used: Watering every 3rd or 4th day, every other watering gets FoxFarm nutes around 1/2 strength along with 2ml CalMag and some molasses. I couldn't figure out how they were showing nute burn with this mild of a feed schedule until I realized the soil was hot.
-Water source: Tap water left out in a tub for a few days, run an air stone in it for 10 mins or so before watering. pH is always 6.3-6.5 and watered until slight runoff occurs.
-Strain and age: Critical Auto, 62 days old. Still small flowers, gonna be 4+ weeks I'm pretty sure.
-Climate: 68 - 81 Degrees, it got up to 88 during peak hours for about 2 weeks, humidity has been 50-80+ the entirety of the grow so it helped shield them. Temps are now 68- 81 but humidity is still high, It's def time to lower it, guess I'll be investing in a dehumidifier...
- Light used: 300w Mars Hydro, have 4 of these in a 4x4 tent; 1 per plant. 18/6 Lights, 18" above canopy
-Additional info: Started a week or 2 ago with mild yellowing and 1 or 2 leaves showing brown spots, progressed rapidly. I thought just this one was affected but I see similar spots appearing on her sister's mid fan leaves as well the newest growth at the canopy. My soil pH probe reads 6.5 in pot for the most part, small fluctuations in different areas but that is a solid medium.

@Waira Thanks for all of your help, wish I could send you a few 'thank you' nugs at the end of all this!

I plucked a leaf to photograph in regular lighting, after lights go out tonight I will take full plant pictures with no blurple lights.

 

[Waira]

...I need whole plant pics in normal light mate, color rendering is shite with LED,.. and color is a key diagnostic clue,... That said, this is a very odd necrosis pattern,.. but the way it's hitting along veins, looks a lot like Mn defc....

.......... Ca on rare occasions can look similar, but I don't think that's the case here,... Problem with hot soils is, they may have decent NPK in there, but the micronutes may not b well amended, so you end up fert'ing lightly-- too lightly, and edn up with imbalanced inputs,... most micronutes aren't mobile within the plant, so a steady albeit low level supply needs to be around all the time,... Also, an in-pot pH check is warranted.... many micro's start to lock out by pH 6.8>,.... with your softer water, and low level Ca-Mg inputs (I think, how much molasses are you putting in? -- it has Ca, Mg, K, a little Fe), I doubt it's too alkaline in there, but it's not out of the question,.. some soils can end up with too much lime, and this forces the pH to stay higher than it should,... So point is, this is probably a simple lack of type defc., but we need to make sure first,...you're adjusted pH is not reflective of actual in-pot pH, too many other influencing factors in play! What pH probe do you have? Most are pretty dubious for accuracy, if it's the skinny probe types,.. only one I find that good is the Accurate 8 (Control Wizard),... and any of them do need to be used properly to get a good read; buff the tip clean, fresh untarnished metal is necessary for a good read,... has to sit for a couple min. too,.... but at least with a 6.5 read, likely it's OK enough,... if it was 7.0, 5.0, it'd be a concern,...
If this is Mn defc. the best way to deal with it is a dedicated micronutrient supplement, like Earth Juice Microblast,.. soil and foliar treatment,... the luxury uber treatment would be with Optic Foliar Transport and Microblast! Transport is frikkin' magic,.... Cheers mate, thanks for the kind senitments on the nug-shares

 

[MakeItRain69]

Thank you, she's been getting 1 tsp. per gallon molasses and I have the Accurate 8 (by means of your recommendation) and it's giving me between 5.9 and 6.9 everywhere in the pot, most readings coming in right around 6.5. As soon as lights go out in about 7 hours I'll get some good pics of her, in the mean time I'm looking in to the optic foliar, stuff looks like magic.

 

[MakeItRain69]

Here are two different plants you can see both afflicted by the same deficiency. Lower leaves and newer upper leaves coming out of the buds are showing the worst symptoms.
First pic is Blue Pyramid Auto, second is the Critical Auto who was the first to start showing this and the farthest progressed.

I have Optic Foliar Transport as well as Earth Juice Microblast on the way, probably won't receive it until midway through next week.

In the mean time, I gave them a healthy dosage of Tiger Bloom that contained .06% Mn, hopefully this will stave off further deficiency until the juice arrives for a foliar.

 

[Waira]

... huh, odd spread, though different levels in=pot can have variable pH, bottom usually the worst... 5.9 there? 6.9 is too high, and that will lock out Mn and others for sure,... using the A8 needs a few pointers: always buff the tip clean before use after being stored, and wipe clean with a damp paper towel or something between uses... the bimetal tip works best when no tarnishing/corrosion is affecting conductivity between the metals,... take readings when soil is well moistened, not soggy or any kind of dry, nor fertilized within a day,... it needs to sit for a couple minutes to stabilize,... mid-pot depth is best,.... see what all this does for a reading,...
...skip molasses for now, no need.... keep the P/bloom nutes coming though! ...-excellent on the EJM and Transport! Did you read up on it? We have a great section here with OF, and i have an thread showing the EJM + Transport use there,... use the EJM at half strength, as per instructions on the Transport bottle,... no need for any wetting agents!