Brown spots on fan leaves

[40ozSkunk]

this is my second grow. I've done lots and lots of research, as well as browsed many "problem" threads on this site and others, but i'd still like to get other more experienced growers' opinions on what my issues are. So here's a little info.

3 gal smart pots/FFOF
gamma kush and super lemon OG (both indicas)
platinum led p300 light, 18/6 schedule, 22" above tops
i started veg on 7/6 when i had my first set of 3 prong leaves, so they're 2 weeks into veg.
haven't been fed any nutes yet
temps stay between 70-84f
humidity has been between 50-63%
water with distilled which i haven't adjusted, but ph is 7.1-7.2. i water when the pots are light, usually every 5 days or so as of now.

the smaller of the two plants is super lemon OG. She's smaller than the Gamma but actually has more nodes and leaves. The lemon is looking healthy, no signs of defects. i topped the Gamma a few days ago.

The gamma kush (which by the way is a bruce banner #3 x Heirloom OG) has some brown spots on the lower fan leaves, and I'm beginning to notice the start of them on the newer fans. I haven't fed them any nutes yet, and other than these spots on the Gamma, they both look healthy. I was thinking adding a little cal/mag into my watering might help, but wanted to check with you guys first. Any thoughts?

please excuse my poor quality pics. i was trying to hold my led glasses over my phone, and well, yea.
pic1 shows them both looking good from afar

pic2 and 3 show my leaf problems on the Gamma. I'm not having these issues on the lemon.

 

[jojo677]

To me it seems like a calcium deficiency. Since you are watering with distilled water with no nutrients, your plants aren't getting any trace nutrients like calcium and magnesium. Plus plants growing under LEDs tend to need more calcium/magnesium than other light sources. You'd be better off watering with tap water, probably. Can you measure the PPM of your tap? Otherwise you can add some cal/mag to your distilled water.

I'm betting either your pH or humidity is a also a little bit low too. I only say this because because some leaves are curling downward. When I used Ocean Forest, I had both of these problems. My pH was like 5.1 (bad) and my room had a very low relative humidity. I had to use lime to raise the pH and got a humidifier.

 

[NuttyProfessor]

To me it seems like a calcium deficiency. Since you are watering with distilled water with no nutrients, your plants aren't getting any trace nutrients like calcium and magnesium. Plus plants growing under LEDs tend to need more calcium/magnesium than other light sources. You'd be better off watering with tap water, probably. Can you measure the PPM of your tap? Otherwise you can add some cal/mag to your distilled water.

I'm betting either your pH or humidity is a also a little bit low too. I only say this because because some leaves are curling downward. When I used Ocean Forest, I had both of these problems. My pH was like 5.1 (bad) and my room had a very low relative humidity. I had to use lime to raise the pH and got a humidifier.

i agree

 

[40ozSkunk]

i gave them a half dose of cal/mag yesterday morning. Hopefully that will help. I don't have a TDS meter or whatever is needed to check ppm, but i ph'd my tap water at 9.14. Plus I'm pretty sure there's dead bodies in our water supply

i suppose its time to introduce veg nutes to them? I'm just kind of leery about using nutes, since I think i overdid it in my last grow. And i always hear about how hot FFOF, so don't want to add to that...

Humidity can't possibly be an issue. It's been sitting at ~60%, and given the surrounding area..

either way, thanks for the reply. we'll get it worked out.

 

[jojo677]

The cal/mag should solve most of your problems. See how they react over the next few days, and you may have to bump it up to a full dose.

FFOF is pretty hot, and it should last awhile. I'd guess you have another 2 weeks without a need for nutrients, but if you're worried about over-doing it, maybe just wait until you get a little bit of yellowing of the bottom leaves, then start feeding them. Usually it's better to underdo it than overdo it, many fewer problems and easier to fix!

 

[40ozSkunk]

for anyone else that might have this issue, the plants responded well to the cal/mag. All the new growth looks healthy and green. ill report back later if i start seeing spots again.

 

[PTSD 4 ME]

Solid advice Jojo.... Also I am sure you have this but its a good picture to post in the grow room.

There is no calcium deficiency on this one tho.....

 

[jojo677]

Glad to hear they're doing well. Keep that close eye on them and they'll reward you well!