I just had mine hit 160 last week.
(I had it test at the LFS and they confirmend my results)
Your test may be not be accurate for some reason, you could try testing it with another kit.
I did 2 50% water changes and will do another one in the next day or two.
Mine are down to 40ppm at this point.
I was really scared to do that drastic of a water change, but it work for me and everything seems to be doing well again.
I would try doing daily water changes of like 10-15% and see if that worked before adding any chemicals.
Jessica