I'm curious about this method. I would have thought that even with multiple purges of CO2 there would still be a reasonable component of oxygen in the collection container, that would be introduced to the brew. Similar to trying to purge oxygen out of a keg by pressurising with CO2 and burping the PRV multiple times, you can't force all the oxygen out. Dropping hops in through the lid would seem lower risk of introducing unwanted oxygen, particularly while some fermentation is still occurring and CO2 is being gassed off.Hey Daz, you can already do this (purge dry hop of O2) with the standard collection container that comes with the FermZilla by adding a carb cap to one of the ports... I will link a video to Gash where he shows the process:
You should check out his other tips & tricks videos as they are quite useful!