Sorry for the late reply, somehow I didn’t get an email notification that you had posted!
At any rate, we don’t ever recommend going below quality 50 because of the amount of quality loss. Once you go beyond (lower than) 50, the gains are not very great, and so it’s usually not worthwhile.
Honestly, I think even 50 is a bit of a stretch unless you don’t mind poor quality images, but ultimately it’s up to your discretion as to how much quality loss is acceptable for your audience.
@nosilver4u my site is viewed 90% on mobile device, so image loss is barely visible. I need it to load fast so I set it to 30