For my conditions, it seems that 50/50 hardwood saw dust/wheat bran is performing better than standard masters mix. It's probably a hair too humid for it in my tent, but it's gotta be higher for the oysters that are fruiting now.
(That is a 5lb block of substrate)
Thank you again for all the info. I doubt I will grow much or any, but it's nice to know about so it doesn't seem so frightening. I thought you were growing mold for a fermentation when I first saw this. Ty again !