"NaCl" Rock Salt by Nucleus. While most salts can work when cleaning out a bong, Nucleus' "NaCl" Rock Salt is coarse enough to really get the job done. The thickness of the rock salt makes it perfect for scrubbing the inside of the glass. Pour "NaCl" Rock Salt into a piece followed by some Nucleus "IPA Clear", plug up the openings, and start shaking. The combination of alcohol and salt does wonders on the residue and leftover debris. Pour it all out, rinse, and voila you have a bong that looks like new.