LED panel hanging height is the eternal unanswered question it seems! I'll be honest and say that we have customers in every extreme and all inbetweens.
We have some customers that swear by letting the tops get so close that they're practically touching the glass of the panel.. and report no problems with bleaching or burning.
We some 420 members like Tav.. that like them up higher around 20"-24". Curso likes them around 16".
The sweet spot does seem to be from 12" - 18".. and that's what we recommend to our customers. The best thing is to find what works for you in your particular situation, with your strain, with your environment.
Therefore.. the best height.. is the height that makes your own girls the happiest..
Oh they're well under 16" now more like 8 from the tallest top, nothing bad to report about it though.
Your looking good over here Poly