Hi
@Kanno26 - glad you got the Rh up a little. I'd like to echo two things
@Verbalist said that I 1000% agree with.
1. Like I told you, if you can't get it up they'd be okay. He is right about why we prefer it a bit higher, but they'll grow anywhere in the range he listed.
2. This is WAY more important: he's also correct about the extent of your stretch. Pump that light up. They only stretch like that if they want more. I'd be at around 400 ppfd at this point if it were me. Worry not, cuz that extra stem you have already is easily fixable. For now get them to stop stretching vertically.
Question: do you have just a *little* air moving them just a *little?* I'm talking a jiggle, not even a light breeze. The plants are never too young to begin to do what they naturally do to strengthen their stems against wind. I would be making sure you have them jiggling if you can, just me, but I think many do this. I always have.
Question: Are you using or going to use any kind of silicon product or better yet MSA? This drastically aids nutrient uptake and stem strengthening. I swear by the stuff as I know many do. You may want to consider such a product if not.
So far your stretch is not causing any major problems, just stop that and you're good! And it's so easy!