Spots in and on leaf tips

dechlorinate your water plus what @asnoriu said. ph issue possibly and cal mag symptoms. but chlorine can cause similar issues and is an easy fix to do before adding or changing nutrients and ph which may be affected by other things rather than a nutrient deficiency or a wrong ph.

Hi, it looks like it's too warm for them, that could be from the lights. I would only turn on the fan at the end of week 2 or the beginning of week 3 anyway. Water at the beginning with a pH value of 5.8 to 5.9, and as the plant gets older, gradually increase the pH value until you reach 6.5 in late flowering. I would start with the nutrients in week 2 with an EC value of 0.4 and also increase slowly. It's 1.6 or 1.8 in boost. Lower the lights only when the plant has a good number of leaves but not too low either. For example, use the Photone app, which shows you the PPFD value. In the growth phase, it’s enough from 400 to 600, and in flowering, then up to 900. Good luck!