I checked with digital humidity meter and it consistently shows about 95% RH (99% when light is on) and there are droplets of water inside all the time (even if not misting).

Now I uncovered more holes and misting once/twice a day to compensate for water loss by evap. and the shrooms are doing just fine.

It seems the humidity skyrockets when lighting is on, the flurescent tube produces suprisingly high amount of heat.

I don't want to uncover bottom holes as the perlite falls through making mess and don't want to uncover top holes as the water vapor may damage the light tube, making electric shock hazard.

Yes I will buy a PC, but don't want to buy some small one (most don't even have a spacer) so I am saving on an 18L autoclave.

BTW Nice to meet you Rick, I hope Morty's doing well (at least in this universe  )