Congrats on hitting it! So first of all your system is perfect for a veg station to feed a flower station in rotations. You could also use it for flower but the total dimensions of your container is too small to accomodate 20 - 30" plants. Of course it makes a difference whether you mean that height at the beginning of flower or that height at the end, but either way that is too big for that container method.

If you want to get to that size you need to use a bucket system typically.