Hey guys and gals, any idea what this could be?

[OBrien]

My first thought is calcium deficiency but I feel like their too young to be showing calcium deficiency.
I’m growing in DWC
Hydroton and grow stones
RO water (another reason I believe it’s cal-mag related)
Nutrients are mega crop and botanicare cal-mag.
Sorry if I left anything important out, just ask. I’m open to any suggestions and advice as I do not want these babies to die. I gave them a light dose of cal-mag and there ppms are at about 150-200ish.

 

[OBrien]

Or could this be a toxicity? Any help is appreciated

 

[West Hippie]

Here’s what’s in GWE
ou may see the brown burnt edges first, or you may see the yellowing first. When the leaf symptoms are both present, it’s a good sign you have a potassium deficiency in your leaves.

Plants may stretch and stems may become weak, but leaf symptoms are more noticeable. The leaf symptoms appear somewhat similar to an iron deficiency in that they can turn bright yellow, but the tips of the leaves curl as the edges turn brown, burn and die.



Cannabis potassium deficiencies can cause your cannabis leaves to turn white, yellow, brown or burnt looking, but the inside veins almost always stay green. Sometimes a Potassium deficiency is made worse by overwatering, as was the case with this plant.

 

[West Hippie]

Here’s one that looks more like yours
Sometimes accompanied by a Calcium deficiency, as Phosphorus and Calcium interact with each other in the plant.



A cannabis phosphorus deficiency usually appears with some or all of the following symptoms:

• tends to affect the lower and older leaves of the plant
• sometimes a phosphorus deficiency is accompanied by bright red stems (though not always), though if you have red stems but no other symptoms, it’s typically not something to worry about
• leaves darken (turning a dark green, blue or grayish color) and may appear shiny
• leaves may start turning yellow in places if the phosphorus deficiency is left untreated, or if the deficiency is combined with other nutrients deficiencies and/or pH problems. However, yellow leaves is typically not associated with the beginning of a phosphorus deficiency.
• leaves get bronze, purple or brown spots and splotches
• leaves thicken and may feel dry or stiff
• stems sometimes turn bright red or purple, but not always
• sometimes accompanied by a Calcium deficiency, as Phosphorus and Calcium interact with each other inside the plant
• this deficiency is more common after buds start forming, when the plant is using a lot of Phosphorus

Phosphorus deficiencies in the vegetative stage usually appear at the bottom of the plant on some of the oldest leaves, and will progressively climb up the plant if left unchecked.