buildup is natural because the smoke does have particles in it and with every inhale some may get trapped in there or if you dont blow the smoke out of the hose. there are filters for sale from Hookah-Shisha
. there may be other vendors but none i can think of off the top of my head but you can use that and inhale very quickly and dislodge anything in it. you can also get your hose and whack it (not super hard but a few times where there is a little force behind it but not enough to bend the coil inside) on the floor to loosen anything then you can blow out or inhale. if you want another thing than filters you can also use cheesecloth to do basically the same job of catching the particless.