Just gonna say VPD charts are not accurate and should never be used.
@sshz I think your squat issues come from 3 places...
1. Genetics (nothing you can do)
2. Spectrum (additional red will help shift the ratio of the type of growth) but the lower intensity I can say almost certainly will give less growth in terms of plant mass with HPS. It will stretch them out but I kinda got a feeling you'll end up losing out on more bud sites. The only reason I say this is you are losing intensity which is the real driver of growth.
High Blue ratios will create more vegetative growth. Red will produce more shoot growth.
Now you probably don't want to spend more money so maybe a moot point but additional IR will IMO help get structure to where ya want... the crappy thing is idk how much it would take to even make a recommendation.
3. You temp differential. I believe day night temps are the same? Possibly even higher at night?
This can largely affect the node spacing.
I can't say that 1 single thing will give you what your looking for in terms of structure. But if I had to guess it would be IR that would make the most difference.
I remember when you first posted here I was watching your thread closely for this exact reason (not sure if you remember that) I wanted to see how well it flowered under a much more blue leaning spectrum than my 3000k
HLG.
Just throwing this out there for discussion and I'm sure you have considered these options but figured I'd put my nosey $0.02 in anyhow.
Definitely will be watching as there is always something to learn from your threads and so well done on providing info.