Use some plumbers tape. I think its called Teflon Tape, can pick it up at wallmart or anywhere that sells common hardware tools. You thread it around maybe 5 or 6 times real tight so the treads are still noticeable under the Teflon tape. Best part is that Teflon tape itself is used by plumbers as a sort of gasket and it will work the same for you by creating an airtight seal. Once you clean your hookah a few times you'll want to remove the old tape and put on some new stuff, 1 roll of Teflon tape comes with enough tape to keep retapeing your hookah for 6 months to a year. Best part is it only cost a few bucks.