DunDermaanswered grow question 4 years ago Hi!
According to the manufacturer the recomended brightness is 50% for Germination, 50-75% for Seedling stage, 75-100% in vegetative grow, and 100% in flowering.
With this information in hand, I would suggest something between 60-100%, maybe 75% or even 100%.
I personally believe that 100% is better than 75% during this period though.