I would keep the MH on for a while more. Until you really see them slow down on upward and outward growth. Best thing you can do now is open them up with some lst. I saw one pic you mentioned lst but the tops were still up, you should take that top and gingerly but 1/2 way aggressively bend it down with some string. Just go slow but you can basically bend it right over, just go easy and when you think its enough stop for the day. You can attach the string to the plant a couple nodes from the top growth, should be very flimsy there and easy to bend. Try tucking those big fan leaves under a new shoot to expose the new shoots.
I agree with the others on your ph 5.5 is low, mine is in the 5.7 drifting to 5.9-6.0 and adjusting back down to 5.6-5.7. I check daily and record adjustments etc.
Roots look great too, big mouth for the plants to feed.
Congrats, and the runt is coming back, looked kinda overwatered, but looking better.
Good vibes sent, keep it going. Its a marathon not a sprint.