Its funny, back in combustion days I would let water stay in my Toker II for a week or more. Today that would make me puke. Vaping has made me a flavor snob and I change my water every day and use CE to keep the glass clean.Daily cleaning is required or you are a BAD person............clean your glass.
dark crystal is food safe and also recommends you use it in the same way you would use CE to help keep it clean, its actually pretty dope works well. Its main use for me is for actually cleaning thoCE is added to the bong water to coat the glass while you are hitting the bong. It is food safe and not a problem to inhale. It is meant to be consumed and not as a cleaner. A glass cleaner is likely to be neither and probably shouldn't be added to bong water. While it is advertised as non toxic, and I imagine it is perfectly safe to clean your glass with it, lungs are very sensitive organs and I don't think I would want to breathe through it. YMMV.