Critical Purple: Leaves slightly yellow.

You have answered your own question.............minimal nutrients! Hydro/DWC or systems like those require you to provide everything. Skimping on nutrients results in plants not growing properly, i.e. turning yellow after only 2 sets of leaves.

Give her some Nitrogen and check the PH. No problem after that. And it will be a one and done fix. As N deficiency can be fixed in one watering.

For a plant this age and size, it's highly unlikely to be an underfeeding issue lol. Considering you're using drip feed irrigation and your hydroton looks soaked, the base of your plant is probably staying too moist. I'd let it dry out a bit. I personally never understood the need/popularity for a drip ring in DWC. An aggressive bubble in your reservoir will adequately mist your net pot enough to encourage roots to emerge.

Hello my friend, the cause for the yellow leaves is because of the wrong nutrient solution. There are 2 options here. Number 1 is not enough (or wrong) nutrients with not enough Nitrogen. Number 2 is the wrong pH value not within the range from pH 5.8 - 6.2

Yellowing is not typically caused by lack of light in indoor grows. If this was the case that means anything under a full lush canopy will yellow. This looks like an issues with not enough feed. You will want to increase your feeding concentration to match the rate of growth. Its best to use a tool to calculate this like a EC pen. EC is universal, some pens use PPM and that uses a scale, eg. some pens 500PPM=1EC others its 720ppm=1EC so know your pens conversion if it only does PPM most pens in North America use 500scale, and EU I think its the 720 or 650 rate. Also given you are doing a DWC style grow, you will want to monitor the temperature of the reservoir. Want to keep this below 21 at all times or it encourages bad things to grow in the water. Your hang height for the light your using according to its web page should be aorund 18" This is the product page from AC: Https://acinfinity.com/hydroponics-growers/led-light-boards/ionboard-s24-full-spectrum-led-grow-light-200w-samsung-lm301b-2x4-ft-coverage/#product-description Check you product Manuel it might have different recommendations for hang height on seedlings, but in general Cannabis can tolerate a lot of light from seed. aorund 35-40 DLI seed to harvest. If it goes over this amount it can harm the plant unless other factors are boosted like CO2, I would not worry about that right now though. something down the line if you want to really get into it. Need a sealed tent for that stuff or the CO2 just leaks out. You can calculate your DLI using the ac infinity PPFD maps provided just google how. Average out the PPFD to get a single number. or use the max value dead centre and know its at this and below on the corners where it fades out a bit. Good Luck!