Manganese deficiency?

[Wajionau]

Please help with my problem. Growing in coco coir. 4 plants same strain, but one plant have this problem with fan leaves, the other plants feels good. All the plant have the same food with drain to waste.

 

[Creeperpark]

It's not a manganese deficiency. There's something about having plants in corners they seem to always run into transpiration issues. If you have one plant that has problems and three that are doing good on the same nutrients I would say that the one plant that is having transpiration issues. It's not moving enough water to push the calcium where it's needed. Hang strings in the grow so you can watch the air movement. Make sure you are moving the air vigorously to move moisture while the lights are on during the day and extract the night air out of the area at night.

 

[Creeperpark]

It's a watering issue. If you overwater your plant and you have a lot of calcium (cal-mag) in the water the calcium will bronze the leaves. Also if you let the roots get too dry it will cause calcium to be unavailable. Transpiration issues, over-watering, or under-watering is the problem. You got to figure it out since you have the plants. Keep us posted on what happened.