You're going to need more light. The effective light from the fluoroescent tubes only extends a few inches. Your set-up is fine for seedlings or young clones, but insufficient for longer-term.

I use the 18/6 schedule for the growth phase. The plants seem to appreciate it more than 24/0.

With the Miracle Grow, I'm pretty sure suggested dosages are for a two week period, not weekly. Cut the nutes in half if you were thinking it was for one week.

Growing indoors isn't a plant-and-forget kind of garden. You'll want to find a way to test your water ph, you'll need proper lighting for the phase they are in, ventilation and circulation...

Without the basics for indoors, the plants will struggle to perform.