Sorry!
I blast outdoors.
I thought it was filtered then placed in the freezer. I understand what you mean. Let it run though the filter while in the freezer. I still do the initial hot water bath purge before this though?
Right now, my bho process is as follows:
Grind weed with hand grinder; tightly pack tube; blast into deep pyrex dish; surround dish with hot water until it stops visibly reacting; let sit as long as I can afford to (usually overnight); and surround with warm water when I get ready to scrape it...