I have a problem of noise (>20 pA, >100 Hz) which is not AC origin (not 50/60 cycles). I have a good faraday cage grounded. This cage can work against the AC noise, but not that strange noise.
I found over the wall that there is a big freezer. However, I cannot change the place of both freezer and patch setup.
I did all what I know, but I cannot solve this problem. If you have the similar experience, I would appreciate for your advises. What is the possible causes and how to get rid of such noise problems?