Help! Not sure what’s causing these issues on my leaves

[Oblivi0us]

I am in week 4 of flowering. Temps are 75 day, 65 night. Humidity 30-50. Have dehu Light is 315cmh in a 4x4 tent. Has heat blowing in bottom when needed and exhaust fan pulling air from top. Have oscillating fans. Using h3ads formula, with slight modification to adjust to plants needs. 4ml micro, 10ml bloom per gal, ro water. Ph 5.8. Ec 1.6
Just started getting these spots and it’s only on like 4 or 5 fan leaves that are closest to the oscillating fan side. doesn’t seem to be spreading to other leaves yet but still worried

I was watering twice a day to 10-20% runoff but after seeing these spots develop I decided to back off to once per day.

Not sure if it’s fungus or nutrient deficiency? Any help would be really apprecited! Thanks

 

[Oblivi0us]

Also on one leaf to experiment I cut off half of a fan leaf blade that had the spot on it and it seems to be fine hasn’t spread anymore on that leaf. I was told by a few others it was a potassium deficiency. Just really hoping it’s not fungus . Thanks again for any insight

 

[Beachwalker]

Only replying because no one's answered because White powdery mildew is one thing I've never had at least in this Century so I'm not the one to tell you that's what it is because I don't know, might be something else? The curled Leaf edges are usually from Heat. Somebody else with wpm experience could help more, good luck!

Ps. Whole plant pictures often help, and if it is wpm copper fungicide is the way to go in my opinion

 

[Madbud]

Wind burn from the fans?

 

[Dirtbag]

It's not PM. Could be from overfeeding, I see some burned tips in there.

 

[Seraphine]

looks more like nutrient burn. See if the damage stops after reducing to feed per day. I would also adjust your pH so you get a range. Keep it between 5.8 - 6.2. Some nutrients like calcium are absorbed at a pH above 6.0 in coco. If you find your coco is drying out too much when feeding one time per day, then reduce your EC and feed 2x per day. My ppm is 500-600 per fed with is about 1 - 1.2 EC

 

[Jimster]

Since you are using RO water, have you supplemented the plants with any Magnesium products? A foliar spray of a dilute epsom salts solution will provide the magnesium but bypasses the roots. If you are getting a lockout, it often looks like a deficiency (which is what it actually is). I'm guessing that you are providing plenty of potassium, which is a common component of most blooming additives. Magnesium is often overlooked and too much Cal-Mag can actually make it worse by raising the Ph above Magnesium's availability range. Nutrient burn doesn't always show up right away. I would re-asses what you are feeding and how often, as well as give a dilute dose of Magnesium via epsom salts and foliar application. It won't hurt anything (as long as you don't make it too strong) and will quickly show results. I often see twisted leaves with nute overdoses, which I don't see. Hopefully it is an easy fix.

 

[hawkman]

Reference: "Grow weed easy.com" and "I love Smoking invalid.com" -- they have pictures of ALL leave issues - Good reference tool !!!

 

[Oblivi0us]

Awesome thanks for all your replies! As more time has went by it does seem to be nutrient burn from watering twice daily. Yes I started adding cal/mag to the mixture as of a few days ago. I also checked my ec and ppm again and they seemed way too high so I started diluting it with more RO water to get it down to 1.2 ec and 700-800ppm. Here is a whole plant picture. There were only a few leaves that were bad but I get terrible ocd and the need for perfection.

 

[02trueblue]

Overall she looks real happy! I bet she'll keep going strong with the slight reduction in feed strength. She looks a little overfed but she looks good for sure!

How many PPM of cal/mag are you adding?