HELP! Lower Leaves on Seedling Splotchy

[carefulwatch]

HELP! Lower Leaves on Seedling Splotchy


The lower leaves (my first set of "real") leaves started developing this splotch on it. It's not tiny brown spots like I have seen in other nutrient deficiency pictures, but big splotchs.
The new leaves appear to be growing in fine! I am wondering if I messed up by watering the seedling with purified water...

Here is my setup:
- NL Auto
- Growing in Coco, following the grow weed easy coco schedule
- Kept it on seedling strength nutes for an extra week because my seedling was so tiny
- Transferred it from a solo cup to a 2 gallon because roots were starting to grow out the bottom of the 2 gal
- 450 w LED lights hung 24 inches from seedling
- Temp 70F
- PH'ed water has been about 5.75, which i read is within the range for coco


Here is is a couple days ago:
https://imgur.com/DqgSRw0

And here it is today:

https://imgur.com/L2UTBap

Should I be doing something? Remove those old leaves? Change my nutrients? More or less? Thanks!

[Gluteous]

I might back off on the feeding for the next one or two and just keep an eye on it. If no other leaves are affected and new growth continues, I wouldn't stress it.

[carefulwatch]

I might back off on the feeding for the next one or two and just keep an eye on it. If no other leaves are affected and new growth continues, I wouldn't stress it.

Thanks!! I have been watering with plain water ever other water. Do you know if I should still be using CalMag in my plain watering because I am using coco?

[Gluteous]

I'm a dirt guy. Check out this article though. https://www.cocoforcannabis.com/needcalmag/