Spotty leaves

This plant is a couple weeks old. Noticing spots forming.
Any ideas what may be happening?

Its in promix potting mix with added perlite.
6 gallon octopot system.
2 HLG 135s at about 25% power
No nutrients yet.
Water ph at 6.

You should start feeding........promix is not like soil.

Do I need to add fertilizer to PRO-MIX?

Yes, PRO-MIX contains a starter fertilizer to help plants acclimate to a new rooting environment. We strongly recommended to initiate a fertilizer program within 7-10 days after planting. The fertilizer program you select should take into consideration water quality, crop type and the stage of plant growth.