Rust spots on leafs

Well I'm 3 weeks into veg, on my second grow & need some advice.....

I'm growing 5 gsc (girl scout cookies) in 3 gal containers, I'm growing in happy frog soil, I'm 3 weeks into veg ,I'm using a 400 wat mh light on 24/7 I been PH'ing all water to 6.8 - 7 for soil
I gave first nutes two days ago at 1/4 strength ( nutes im using floranova grow)
All 5 plants are lst (low stress training)

The problem is I noticed brown spots on lower fan leafs start to appear , it's just on a few lower leafs on each plant but you can tell it's getting a little worse but it's just starting I would like to properly diagnose this deficency so I can take care of it before it spreads any more here's a few pics
[/ATTACH] I did some research and googling to compare pics of the deficency & I was thinking it was a cal,mag deficency???(not 100% sure, so I need your thoughts....) so I gave them a dose of calmag to day hoping it will clear up but any advice and in put is needed thx in advance

The affected areas won't "clear up" just keep from happening else ware.

MoMoGrows said:

The affected areas won't "clear up" just keep from happening else ware.

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So do you think it's a cal mag deficency???

Kinda had the same thing happen on one particular strain / I add dolomite lime as a top dress and redid PH slightly Lower to 6.3 - 6.6. It stopped it.

I noticed some strains are a little fickle about their PH range and the main issue was PH FLUCUATION. I discovered runoff was off. I'd say check run off to see if there is a noticeable difference.

Truthfully I don't know, not my area of expertise. That was my first guess tho, but only a guess. But having a cpl replies usually attracts other people to reply. PH seems lil high.

Budzbuddha said:

Kinda had the same thing happen on one particular strain / I add dolomite lime as a top dress and redid PH slightly Lower to 6.3 - 6.6. It stopped it.

I noticed some strains are a little fickle about their PH range and the main issue was PH FLUCUATION. I discovered runoff was off. I'd say check run off to see if there is a noticeable difference.

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Il check run off next water but the dolomite lime how do I use it and how much do I use????

Whats your ventilation like? I dont think it will be rust fungai, budz buddah is right check your run off it will be a ph problem.

lfc89 said:

Whats your ventilation like? I dont think it will be rust fungai, budz buddah is right check your run off it will be a ph problem.

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Ventolation is good 450 cfm exaust fan with charcol filter exaust ing hot air out side , air conditioner keeping the room temps to 75 night 77 day ..it's not a fungus definitely a deficency.

Looks like maganese deficiency

Be careful those pots hold a lot of moisture in the bottom 1-2inch and can cause you problems down the line ive been running them for a year+ and just switched a few months back

In soil, manganese is best absorbed by the roots in the 6.0 - 7.0 pHrange (some growers recommend keeping the pH slightly lower, from 6.0 - 6.5, if you suspect a manganese deficiency in particular)

If you suspect your growing cannabis plant has a manganese deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes manganese. This will remove any extra iron or nutrient salts that may be affected the uptake of manganese, it will help restore pH to the proper levels, and will supply the plant with any missing nutrients.

You are looking to avoid higher pH ranges, as this is where manganese deficiencies are most likely to occur.

hells canyon genetics said:

In soil, manganese is best absorbed by the roots in the 6.0 - 7.0 pHrange (some growers recommend keeping the pH slightly lower, from 6.0 - 6.5, if you suspect a manganese deficiency in particular)

If you suspect your growing cannabis plant has a manganese deficiency, flush your system with clean, pH'd water that contains a regular dose of cannabis-friendly nutrients that includes manganese. This will remove any extra iron or nutrient salts that may be affected the uptake of manganese, it will help restore pH to the proper levels, and will supply the plant with any missing nutrients.

You are looking to avoid higher pH ranges, as this is where manganese deficiencies are most likely to occur.

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The only thing I've been giving the plants are straight ph,ed water due to the happy frog soil already having nutes in it, wich last 2 to 3 weeks .so I shouldn't have to flush couse I haven't been feeding them nutes just water so there shouldn't be no salt build up.I gave them there first feed of nutes 2 days ago at 1/4 strength thinking it was a deficency then I gave them a light dose of cal mag today to see if that helps,
But ya these are new pots I'll keep an eye on the moisture

Check the bottom of the leaves for tiny little bugs that suck the moisture from the plant, they usually look like black specs. If that's not it then it could be genetics of that strain or the light may be too close to the leaves.
Hope this helps.

CaliBudMan said:

The only thing I've been giving the plants are straight ph,ed water due to the happy frog soil already having nutes in it, wich last 2 to 3 weeks .so I shouldn't have to flush couse I haven't been feeding them nutes just water so there shouldn't be no salt build up.I gave them there first feed of nutes 2 days ago at 1/4 strength thinking it was a deficency then I gave them a light dose of cal mag today to see if that helps,
But ya these are new pots I'll keep an eye on the moisture

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I just cut copied and pasted all of the info from the article

So I just went out and baught this soil ph tester I tested the soil and this is what I'm gettingIt's looks as if the soil ph is about 7 neutral ..... I think I can probley lower it a little to about 6.5 but how????? Do I just adjust my water and feed to a lower ph like 6.0 when i water or feed ????I been putting water and feed in at about ph (6.9 - 7.0) so should I lower my ph of feed & water when watering & feeding ????

Budzbuddha said:

Kinda had the same thing happen on one particular strain / I add dolomite lime as a top dress and redid PH slightly Lower to 6.3 - 6.6. It stopped it.

I noticed some strains are a little fickle about their PH range and the main issue was PH FLUCUATION. I discovered runoff was off. I'd say check run off to see if there is a noticeable difference.

View attachment 3476771

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I still have to check the run off but here's what soil test looked like

Any one...... no experience growers have ever seen this ????????

CaliBudMan said:

Any one...... no experience growers have ever seen this ????????

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How to lower your soil ph?

Well after giving cal mag the other day I'm definitely gonna say this was a cal mag deficency the plants are back to growing fast and healthy the spotting has stopped spreading ..but I'm still waiting for pots to dry out so I can test ph levels........