Yes, 80% is very dangerous. My basement was at 75% and I even smelt the mold. I puchased a 50pint dehumidifier and now humidity levels are maintained at 40-50%
Theres so much water in the air down there I empty the bucket every other day!
I know I didn’t “kill” the mold behind the drywall or on the studs, but at least its dry down there.

You need to purchase a stronger dehumnidifer! Get 100 Pints. My basement is 425 Sq Ft…