Hi,
I genereted my demux.qzv and I insert it in https://view.qiime2.org to evaluate the quality of the reads. However, the value of Il Middle of box-50th (Median) is under of range 30-40. How will I do? Have I to run (16S Illumina-faecal samples) another time all samples ?
Because the quality drops at this point, you could truncate your reads at that point when running DADA2. See this example from the Atacama soil microbiome tutorial.