See why the form is so important.

You MUST check PH. Shoot for 6.5 as the goal.

This is such a small grow area I am not competent in this. Need someone experienced in these small grow box setups to chime in. I concern about the amount of air exchange.

The plants are showing need for nutrition, should not be that yellow at 12/12 for only 2 weeks. Can you repot into a little larger container with decent potting soil, MG only as a last resort. That should provide most needs, give a very, very small amount of nitrogen, which you probably gave with the MG nutes, so hold on that.

After a couple weeks in larger containers you might give a little unsulphered molasses.....a little.