What is this deficiency?

[Saosin]

Hey guys. I have a critical purple auto on day 40. I noticed what looks like a cal mag deficiency starting, but I'm not sure and would appreciate any help. Only a few leaves in the middle of the plant are affected, but they're getting worse. Temperatures are around 80F. Humidity is 50%. Lighting is a 400w HID and 300w mars led. Soil is happy frog and ocean forest mixed half and half. I'm growing organically and have not added any bottled nutes, just a couple of teas I brewed. It's a pretty big plant and has been growing very well, but definitely has developed an issue. Sorry about the bad quality pics, I had to take them with my laptop camera. But the leaves have yellowing with brown spots. Thanks for the help.

 

[Saosin]

 

[namvet25]

Have you been using any cal/mag?

 

[elcomedito79]

Calcium! Boom!!

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[Saosin]

Have you been using any cal/mag?

No I haven't used any cal/mag or any nutrients at all. Can you recommend a good organic calmag supplement? I hear general organics is pretty good.

 

[Saosin]

So I got Roots Organics Elemental for calmag. The recommended serving is 1 tsp per gallon. Should I cut that in half for my autos?

 

[Mr Green Fingers]

So I got Roots Organics Elemental for calmag. The recommended serving is 1 tsp per gallon. Should I cut that in half for my autos?

What water you using, I use hard tap water and I still need to use the recommended amount as my LED seems to make my girls calmag hungry!

 

[MedGrower]

Soil is happy frog and ocean forest mixed half and half.

It sure seems like Ca deficiency. What is the pH of your soil? I've heard a lot of cases of people using fox farm ocean forest measuring it be closer to battery acid than a proper soil so there is a certain possibility your soil is having too low pH for a proper Ca absorption to take place? Take this as my 2 cents, I am hydroguy and don't really know soils and specially not organic soils

 

[Saosin]

What water you using, I use hard tap water and I still need to use the recommended amount as my LED seems to make my girls calmag hungry!

I'm using R/O water.

 

[Saosin]

It sure seems like Ca deficiency. What is the pH of your soil? I've heard a lot of cases of people using fox farm ocean forest measuring it be closer to battery acid than a proper soil so there is a certain possibility your soil is having too low pH for a proper Ca absorption to take place? Take this as my 2 cents, I am hydroguy and don't really know soils and specially not organic soils

I'm not sure what the ph of my soil is, haven't checked. Everything is growing pretty well. The cal/mag deficiency just started at day 40. I also thought that you didn't need to ph your water when growing organic, but I'm no pro. My r/o water is around 7 ph. I should probably ph it down huh?