First time coco, side-grow

This is my side-grow. I do have 2 girls in flower, but I wanted to fill my room, and I started these as soon as I could. This is my first time (Well second, counting the flowering girls) growing in coco, and I still not all sure what I do, but I will try my best to do right, and learn from this. I am using RO water. The girls are on day 22, and everything seems to go good. I see they are dark green and are going to lay down on the nutrients on the next feed. The girls have been topped around day 12, and later done LST Day 24: Decided to do some more LST on these girls. Girls are growing strong, and looks healthy, other than they are a little dark greenish Day 26: The dark green leaves are getting worse. They are almost shining, and I'm sure I have a Nitrogen toxicity. I think I mad a bum-bum, giving my babies the nutrient water for my grown-ups 😱, so I have given them a good flush with ph 6.0~ RO water, and let them dry out, before giving them a light-mix, and hopefully this will do the trick as they are still growing strong 💪