80 ppm NO3 alone I am thinking can do it. Long-term high nitrate has been linked to bloat and poor digestion in goldfish as well as problems with the swimming bladder and one of the causes of the "float" symptom. I cannot link the scientific paper but that's what I remember.
What test kit do you use to come up with this number?
NO3 in general is impossible to measure at home, even hard in the lab. So those numbers are a very general guidance. Still, everyone agrees that if one uses API MasterKit kind of a liquid test, the NO3 is better be kept below 20 ppm for sure, 5-10 ppm is the best.
Metro and Prazi will not harm your BB's, as Aquanero said.