Orange Spots on cannabis seedling leaves

[omaged]

Hello, it's my first time growing, and my plant (Auto White LSD feminized) is approximately 30 days young, I use water only, with a PH level of 6.5-6.8. it's planted outdoors in a 5 gallon pot with soil containing Peatmos, Fermi-composite, vermiculite, and Perlite. I noticed the orange spots this morning on a leaf. can anyone help me figure out what's the issue and how to fix it?
Thanks.

 

[TysonOG]

Calcium deficiency. Add 2ml of calmag per gallon to your watering routine, every other watering.