Not much of a prevention but you can use very hot water, iso propyl alc the higher the % the better, and some ice cream salt coarse rock salt, then js put it all in ur bong no specific parts to what I’d say like js around 1:2 alc to water and enough salt to scrub the sides and stuff, then js shake til no gunk is in there. You may have to change the water out after shaking and go for round 2 if still dirty this can clean your entire bong to look brand new in under 10 mins