During maintenance today I adjusted weights on the PSL periscope to try to reduce the DARM peak in the 120 Hz region. I reduced the highest part of the peak where the HVAC-produced seismic peak overlaps with a periscope peak,  by about 3/5.  Also, with the consent of Tyler, I shut off SF2, which is mainly responsible for the new HVAC peak, reducing the total LVEA flow from 31k CFM to about 27k CFM. Before the pandemic we ran with two fans pushing about 10k CFM each for a total of about 20k CFM, so I dont think it will be too much of an issue. I have been monitoring LVEA temperature and it looks like the excursions are getting smaller.

The improvement at 120 Hz is looking pretty good, more details later.