These are twins but the one on the right has not t...

Judging by your soil's color, I think you're over-watering your plants. Roots need to alternate between moisture-phases and drought-phases : 0.6L by day is probably too much for your container size and your young plants. Keep us informed, I'll be around, until then good luck with these babies bro !

The one on the right looks like it is underfed. That one on the right is yellowing. Try increasing the nutrient feed on that one, just a little.

Nice start to your grow buddy. Doesn't look or sound like there is anything wrong with your girls at all at the moment. Leaves that are a dark deep green in colour have what you call nitrogen toxicity. - Which would not be good for your plants health, weak stems, deep green leaves and overall slow growth are all signs of too much nitrogen.

The opposite of that would be your leaves yellowing. But a nice healthy green/light green is ok. The same way plant vertical growth varies from one plant to another, so does the colour. Can't expect them to be exactly the same. Your plants are fine. Hope this helps :sunglasses:

Your temperatures are fine, so is your solution strength, no signs of heat stress and they look awesome. Don't panic, everything looks great. If anything give them less water, so to promote better root growth 600 cc of water per day is too much at that stage, try 100 cc or even less.