Whatever you're doing seems pretty effective! Are you running your lights 24h? And if you don't mind me asking what kind of soil are you using and how often do you water?
Alright, that's quite a bit different from some of the other suggestions I've had. I really can't argue with the results you're getting after 9 days! I kinda thought mgro + perlite + nutes would be too much for young plants, but yours don't appear to be burnt at all