I just soak mine in Star San, squeeze it out, and then insert into the flask. Sometimes, it do that in Star San so the more flows through it. I would advise getting a couple more of the foam stoppers. After a while you'll want to replace that one.
Hopping Tango Brewery
跟猴子比丟屎 ・ Gun HOE-tze bee DIO-se
On Tap: Caramel Ale, Mocha Porter II, MO SMaSH IPA
Waiting/Carbonating: 12.5% Wee Honey II, 8.9% Old Ale, English Brown Ale, Lickah ESB, Mocha Porter II
K2: Epic mead
On Deck: Caramel Ale
Mead [bottled]:Oaked Wildflower Traditional, Mocha Madness, Blackberry Melomel, maple wine