Here is an update.
I kept the plant in the same soil until yesterday afternoon, when I finally got the Happy Frog Soil and the Perlite. Before I transplanted, it wad doing real bad. I flushed it two times (once with a decent amount of ST) in an attempt to flush the nutrients out of the Miracle Grow shit. The plant was still droopy, and the leaves were all getting yellow. I even had to cut the first node of leaves because they were dead, yellow and brown. You can also notice some nute burn from the Superthrive in one of the pics. I think the plant was seriously locked out because it was not growing at all (maybe 2" per day and nodes coming at quite slow).
Once I transplanted it, things started looking better. For the transplant, I waited until the soil was dry. I tapped it from the bottom and it came out. I noticed 1/4 of the bottom of the soil was surrounded by white roots. They looked quite healthy. Then I put it into a new pot of the same size (since bigger would not be beneficial I think, it's still a small plant) with a layer of 3/4" Perlite stones and then a mix of 70% FF + 30% Perlite. Most of the MG is still there, but at least surrounded by well aerated Happy Frog.
In addition, I added a box fan blowing at slowest speed. Before, there was not enough direct fluid movement around the plant so this is much better. Temperatures dropped thanks to the convective cooling and stem movement increased due to the flow of air. So hopefully the stem will get stronger.
Good news is that the plant looks much better even after only 1 day!! You can see in the pics that the top leaves are much greener with no nute burn on the tips. The plant grew the most it has this last day. The top node came out about 8 mm, a record so far (for me at least
).
I will keep you guys updated, and sorry for the long post. I just wanted to log my progress in here for other people to study and use as reference.