Is this Cal/Mag deficiency?

[YardDog35]

I noticed the start of this 2 days ago and its getting worse. From the reading I've done here in searches, and seeing pics I have came to the conclusion this is a Calcium and or Magnesium deficiency. Am I correct? Being T-day I couldn't go the local hydro shop, be going tomorrow. I see GH (the nute line I'm using) makes a Cal/Mag additive. Should that do the trick?

A handful of leaves are showing it now. I did a water change and nute add last night. Using GH FloraNova bloom, Floralicious Plus, FloraBlend, KoolBloom, and AN's Bud Candy. GH Sub culture.
White Widow
3 weeks and few days into flower
PH is a stable 5.8-5.9
Tent temps are 77*-81* with lights on, RH is around 50%
400 watt hps with cool tube reflector
Growing in a GH waterfarm with air stones on the bottom

Think that is all the relative info to my question. Thanks all!

The worst leaf

 

[eBUD]

Yes that does look to be the problem. I would get a Cal/Mag addative and start using that as recomended. If you do it fast the entire plant wont be effected it will be just those few leaves. Keep us posted please and happy growing

 

[HB Rob]

Definitely not Mg deficiency, yet. Magnesium tends to bleach out the leaves between veins where as Calcium deficiency will create those brown spots. Grab that Cal/Mag and start using it. These plants suck up more of those two nutrients than even the hardest waters can provide.

Use it as a foliar spray in the morning before adding it to your reservoir. Plants can absorb nutrients through their stomata much faster than through their roots.

Best of luck!

 

[Froglips]

Definitely not Mg deficiency, yet. Magnesium tends to bleach out the leaves between veins where as Calcium deficiency will create those brown spots. Grab that Cal/Mag and start using it. These plants suck up more of those two nutrients than even the hardest waters can provide.

Use it as a foliar spray in the morning before adding it to your reservoir. Plants can absorb nutrients through their stomata much faster than through their roots.

Best of luck!

So you should only use a foliar spray once per day?

 

[YardDog35]

Thanks for the input! Really appreciate it. I picked up some CaMg+ today.

Did a res change and added it. I have lots of leaves that have not been affected so I hope I caught it in time.

Thanks again for the input and positivity

So you should only use a foliar spray once per day?

I'm going to avoid the foliar spray at this point in flower. RH is a little high due to the rain, I don't want to increase chances of mold.
In veg I foliar spray about once a week. Every other week is plain ph'd water.