Chlorine can be bad for cedar if you add too much or use the wrong kind. Dichlor is the gentlest chlorine product available, and no other form of chlorine should be used on wood tubs. It is possible to damage your tub with dichlor by ignoring the recommended amounts, but when used correctly, the small amounts of dichlor will not harm your tub, or you. The recommended doses are detailed in our Water Sanitation Guidelines. For reference, our recommended chlorine dose for one of our bestselling models (6′ Round with ionizer) is merely one tablespoon at a time during break-in, dropping to ¼ tablespoon after the tannins have been released from the wood. These levels are so low that if you hadn’t put it in yourself, you’d never know it was there. You will not notice a persistent odor or feel any effects when using the tub. Some people use bromine for cedar tubs instead of chlorine, thinking it will be better for the tub. It is true that bromine is gentler on wood than some forms of chlorine, but it is still about as harsh as dichlor-type chlorine. We prefer dichlor for one big reason though: excess dichlor evaporates, and excess bromine soaks into the wood. We believe that over time, a cedar tub maintained correctly with dichlor will outlast a tub sanitized with bromine.